Small Engines (Lawn Mowers, etc.): turf tiger wont start, safety switches, commercial man

Question
I have a Scag Turf Tiger (older model) with a Kohler 25hp motor.  When you turn the key nothing happens.  I replaced the ignition switch and the relay inside control panel but neither helped.  I can jump across the solenoid and starter and make it start (with key on) but sometimes it will run 30 minutes or sometimes 10 but it ends up dying while mowing.  I can jump it again across solenoid and it starts right back up but it ends up dying again. I know it is probably a safety switch (there are four). I have tried putting a jumper in the seat switch and the brake switch and makes no difference.  I did put these right back by the way. What do you think?  Do you think it is a safety interlock problem and is there anyway to test this?
Any help is appreciated.  My dealer wants it for two weeks to try and fix.  

Answer
Since the problem seems worse (engine dying) as the unit gets hot it's probably not a safety switch.
The only component that is effected by heat is the control module. Safety switches either work or they don't, heat is not a factor in their operation. I'm guessing the problem is with the control module. #483029, but that's just a guess.
To test the safety switches attach a Ohm meter to the prongs on the switch. Push the plunger in and see if they open and close.
Are you a commercial cutter or a home owner?
If you are a commercial man you need to find a new dealer. 2 week turn around time from your dealer is unacceptable. If you are a home owner 2 weeks this time of year is excellent. As a matter of fact, if he can get you in and out in 2 weeks he's not very good anyway. Most "good" dealers are about 3.5 weeks or more behind right now.
Do you have a test light or Ohm meter? If you do post a rating and I can follow up immediately. If you go through the ask a question page I'll probably be maxed out on questions. Go through the back door, I can respond quicker and it's easier for you. If you don't have these items all we can do is guess.
We can solve this. Give me a better idea of your equipment and we'll go from there.