if your directional contactors are pulling in but you are loosing travel i would suspect the directional contactor tips being worn or the armature parts inside it are worn and hanging up causing it to not pull in correctly and loosing connection.
If you have travel and then not it could be the tips are either burned or just worn enough to not make a good connection every time they pull in causing it to loose connection and have loss of travel.
These contactors when they get worn will also hang up and not pull in completely and as they warm up it can get worse which would explain the increased frequency of travel failure as you continue to drive it.
Take a look at the forward/reverse contactor assembly and see if the tips are burned or flattened out.
Another test to try is to jack up the drive wheels off the floor, get the truck to start acting up again and while it is in the no drive state go to the forward/reverse contactor assy and wiggle the tip assys and see if it returns to driving normally.

Alot of what has been described in the previous threads you've posted is sounding alot like the fwd/rev contactor assy is worn out or burned tips in it.

Best remedy to repair this is to just replace the contactor assy, you can try to repair the contactor assy by installing tip kits but the parts, labor and time to do this would cost more than just swapping it out with a new one.

Although these EV100 systems are known to have issues with the recs #2 and #5 and an occasional #1 failure these are usually accompanied with a fault code. Since you do not have any faults showing this is what has led me to this conclusion about the directional contacts.
If they are worn and loosing connection this would explain the loss of travel with no error codes.

its been a while,, had 3 mechanics look at the lift,,, ended up replacing the motherboard & plugs,,, no fix!
last one tested all relays,& components, said ok,,thought it was issue with speed pot,,(seemed to force to work when speed was increased),, so replaced the part,, but same issue, it definitely seems to be much worse in the summer months,, heat,, humidity? does anyone now what part controls speed pot?

while lift is having issue, (& relays still click) when u push the full drive relay the lift moves, so i would think drive motor is ok

Sorry for my lack of knowledge,, but where is the speed control pot?
thks

how did you check the battery?
did you check the voltage drop under a load too?
Is this a 36 or 48v system?
what voltages did you have after charging, and what was the voltage drop under a 15 to 20 sec load?

if # 2 0r # 5 were bad your truck should pmt, one of the checks in srm was to check that wire going to scr #1. like mrfixit said, check your contacts and accel. pot

You mentioned the relays are clicking even though the truck won't go in your first post? If that's whats happening then I would think you should be checking the relay contactors them self, the speed control pot and wiring, and the drive motor.

The blue is coming from small part #171b3940 (which I guess is also an scr?) the purple is coming out of the big unit marked ev-100 scr

So, the blue wire could control issue of intermittent forward & rerverse?? I will double check the point of attachment at wire harness plug into control panel, could issue be the small scr part#171b3940?
Are wire harness replacement plugs available on line?

the purple wire comes from scr 5 the blue wire is the cathode wire from scr 1 to controller

The only blue wire I see coming out of control is going to snubber not direct to scr,, seems tight and in good shape, have a purple wire coming from scr,, but all seem good

am new to this forum,,, guess no way to post images??

Serial # C114V01568F
Model E30XL

also check the blue wire from scr 1 to control card at pc 9 for a good connection

Inside the pedal itself right under the part that you tap with your foot for direction....swithchs are actuated by a metal plqte and is also a small magnet to keep it in position is simple to remove the whole assembly and look at.....should be a pin that holds the pedal assy. To the teuck with a cotter pin or eclip,remove this pin,unplug the electrical connection and remove the assy feom teuck

Battery is ok,, no lights on this dash,,Out of shop, but when I get back I will list full model & serial #, where would those monotrol switches be?, by the pedal?
Thks

Couple things come to mind....first is what is the battery charge at is the battery fully,charged and verified that its not a bad battery?
The monotrol pedal has two switches that maybe out of adjustment.
Mate there any codes or a warning light lite up on the dash????
Have a full model AND serial number of the truck?