I don’t know what type of controller this, but if it uses the old IBM wire contact relays (and the bigger Potter Brumfield), I’d start there in the leveling circuit and work back.
Sounds as if the generator isn’t the problem, because
The car lifts full load on inspect, but on auto, there’s a problem.
IBM= burnt pins, crossed pins, bent base pins and divots in the NO/NC sides, and failed coils.
PB= Broken shunt wires , worn contacts or contact fingers crooked and of course bad coils.
There’s probably more to this since the model is “Compu-“ whatever.
If there are slot boards…remove, look for obvious burnt components, clean the gold fingers, inspect the contacts where the board slides in if this the case, and reseat. If none of this applies, you’re no worse off than before. GL!
