Hi Leon

I had a similar problem on the shunt wound type Linde, and the problem was the Dead man cut off switch had a small interlock switch inside the dead man cut off switch and that switch was faulty.

On the series would motor trucks, if the interlocks are ok the accelerator is ok and the contacts have been replaced and motors checked ok, then i would guess its a controller fault?

Also just remembered had one last week DC series wound linde, the contactors were coming in but the truck would not drive and the problem was the regen contactor was not operating and when it did operate the tips were not making as the tips were very bad on the regen contactor, this was also an intermittant fault with similar symptoms..