First off I'm not a forklift mechanic but fairly mechanically inclined.

We purchased another company and along with the assets of this company was a "non-running" Crown 30SCTT with charger. I had a wrecker pick up the lift and deliver it to my office and after adding water to the "junk" battery the voltage started to come up on it. Once I got the banks up to around 34 volts I was able to get the big charger to kick on and up till last week we've been using this lift every day without a single issue.

Now all of the sudden sometimes it will move forward and reverse then for no reason it will not, sometimes a slight buzz or clicking from the contacts but the same either forward or reverse. I thought it may be the encoder (potentiometer) on the accelerator pedal which I replaced and seemed to fix it for about 50' then back to the same thing. Just went out there now, hopped on it and went to pick a pallet off the roof of my office then without warning back to clicking and buzzing but no moving.

Where do I begin to look??

I don't want to drop a lot of money into this lift but if there's little DIY fixes I can use to keep it running it's nice to have around here when stuff needs to go upstairs or come down.