good to hear that helped, after looking in the troubleshooting part of the ev100 manual that was what it suggested for your symptom.
Just so you'll know, the #3 rec is the flyback diode, it's purpose is to generate a loop of the stored current in the circuit and motor and is called 'flyback current'.
The #4 rec is the plugging diode, this takes that flyback current and redirects it back into the battery when the direction is reversed during travel so while the motor is slowing down to reverse direction the flyback current is being directed back into the battery.

So if you cannot determine which one is leaking or shorted (i'm betting the flyback #3 is leaking), you should replace both if you cant determine which. The best way to check them is to use what they call a handyman tester which has a leak test mode on it. You can use a vom to test them but you'll need to put the scale on a high range so it can be sensitive enough to pick up the leak through. Remember it is basically a diode so it has continuity in one direction at around 7 to 12ohms and when you reverse the leads that is the leak test part and it should not have ANY continuity at all, if it reads anything it is leaking.
EV100LX manual describes testing the 3 and 4 rec's as follows:

"3REC and 4REC are diode with about 7 to 12 ohms in the conducting direction (anode to cathode) measure on the R x 100 scale, and 10,000 ohms or higher, in the non-conductiing direction (cathode to anode) measured on the R x 10,000 scale."

One of the Recs is leaking. You need to replace it.

So I had one extra Rec from our parts lift. I installed it as 4REC, with 3REC being unknown good or bad. The lift still had the problem. I swapped them around, now it's good. They have the same part number. Doesn't really make sense to me why it would not work the one way and swap them and work fine. Unless if 4REC isn't actually needed.

Anyways this is what I found I hope maybe this can help someone in the future.

First I tried swapping out the spider and all of the filters mounted to it since it was kind of the easiest to access. no change.

swapped 3 and 4 REC's. Fixed. So not for sure which one was bad. Trying to ohm them out and not getting reliable results. So not sure which was bad or maybe both. I have on extra one hand from a spare parts machine so I'll do some experimenting and see if I can figure out which one it was.

Swoop223, you are my hero. Much thanks.

Swoop223... thank you!

We have a sister lift that is up and operational without any known issues. rc3000. I will begin trying the things you mentioned and post results.

although you checked the 1, 2 and 5 rec's i would also check the 3 and 4 rec's, if there are any issues with scr speeds like you describe those rec's can be the cause of no scr variation with an audible hum present.
You should read about 7 to 12 ohms (anode to cathode) and no reading (cathode to anode).
From the sounds of it you have scr hum with little to no power with normal scr hum.
The sudden jumping when you press the pedal would be because your making the 1A switch and it is jumping into 1A speed. That sudden jump causing the huge increase of current all at once across the directional contactors, it could be a pmt trip causing the arc'ing. Then the machine stops after the pmt trip. Reset the key and it runs again doing the same thing.

While your checking components you may also want to consider replacing the 22 and 25 rec's, they can test ok with an ohm meter but still fail under load. Try swapping positions on the spider block where they are mounted or if you have another truck that runs ok just borrow those and swap them out and see if there is any change.

Brewski I just want to say thanks for the reply. That is exactly what its acting like. That is what led us to replacing the drive motors because I could disconnect the right motor and it wouldn't do it, but also wouldn't do anything. We suspected a drive motor was pulling too much current.

I don't have one but I'm sure I can round one up we are a heavy equip. repair shop and we use these forklifts out the ying yang.

With the amp clamp, Where would I clamp at and what kind of readings should I see?

Do you have a clamp on amp meter? It sounds like it is going over current.

IS there any chance that the contactors are incorrect? They were replaced with Part number 116794-005. In the manual there is another one, 123470-001. Both pages for both part numbers in the manual say they are for forward and reverse and both are 24v. The part numbers on the internals are different.

the lift i'm working on is supposedly an rc3020-40 serial number 1A222700

Does anyone have any ideas? I've literally been through almost everything on this machine. I've tried different 1, 2, and 5 rec, capacitor, reactor/choke, took apart EV100 area cleaned everything checked all wiring to verify it is correct. Also tried different 4REC B, 1A contactor, and S contactor. Removed all cables that run from contactor panel to motors, pulled through the bulkhead cleaned inspected, reinstalled. I've tried a different steer motor. all the safety switches are bypassed underneath the pedals, steer switch, brake switch, entry switch. steer limit switches are working as they should, I can completely disconnect them and get the same results. height switch is working as it should , i can disconnect it also and get same results. forward and reverse switches have good voltage drops. All of my inputs to to the circuit board are correct. I tried a different circuit board, and the machine loses power it doesn't have the **** to do anything. It has a new: battery, circuit board, both drive motors, potentiometer, and both drive contactors.

The only thing I'm noticing that is when I'm checking for voltages, if I ground out to the frame of the machine, anywhere, I have strange voltage. Either ,-7, -10, or +25v.
battery voltage is good (36.84 @ connector).....
but (25v with pos lead on battery connector and negative on frame)

Does anyone have any idea or suggestions things to try, etc. because at this point I'm at a loss.

replaced drive motors, same problem. drive contactors spark and machine stops immediately.