The message
from Harry Bloomfield contains these words:

I'm just a bit unsure of how it should be driven - as in I'm stalling
it rather a lot. It is a 7 speed + reverse. I come to a stop going
forward hold the brake on and move the F/N/R lever to reverse and it
stalls and the same when trying to go forward again. If I don't touch
the brake, just move the F/N/R lever it doesn't stall, but surely I
ought to be able to hold it on the brake?

I have a Lawnflite 603. That only has 5 speeds (forward and reverse) but
the cutter won't work in reverse. Not sure if that is from a misguided
safety POV or whether the whole geartrain is reversed making it
impracticable but it sounds as yours will cut when reversing, so is it
meant to or has someone been messing with the cut-outs?

--
Roger Chapman