walker mowers

I have run walker mowers for years but i have a 20hp that is having problems, i was woundering if any one else has had this problem or knows how to fix the machine
The problem is the key swich will not start the mmachine, so i thought the starter i started the machine by the contacts on the starter and it starts rite up. I can turn the blades on runs fine but when i move the forward control to go forward The machine dies. It will go backwards all day with the blades running & the machine...

walker mowers