Help with vintage Nosram

[VintageRacer]

I have, just yesterday, got my son up and running with an freebie Grasshopper and my old Nosram ESC ("Advanced FET Controller") which I posted photos of here http://www.oople.com/forums/showthread.php?t=11263

I've used a Novak lipo LVC and a stick pack lipo and it works ok however

* the car doesn't start up very smoothly, it seems to start at a fairly high speed and snatch at the gear box giving limited speed control, only marginally better than the mechanical ESC we took out.

* there is virtually no brakes and the reverse speed is very slow. The slow reverse I can live with, but the lack of brakes is frustrating.

We still have the 380 size motor in until the 18t pinion arrives and I will put a 540 motor in, could this be part of the problem?

Can anyone remember what the 3 potentiometers are for? 1 is the neutral position adjustment but the other 2 don't appear to do anything. Am I remembering this ESC being better than it actually was or is it dying?

Cheers.