Question for toro experts - groundsmaster issues

[GREENITUP]

I have an old groundsmaster - proline 120 for personal use that just started cutting off when the clutch switch is thrown. I assumed the clutch had burned up because it acted the exact same way about 5 years ago - and it was a bad clutch then and once replaced... worked fine.
So I just put on a new $230 clutch...... still cuts off. Then I replaced the toggle switch that engages the pto..... still cuts off the engine in about 3 seconds. Traced wires for shorts - didn't find any. There is only one fuse on the whole mower..... it's not blown.
Any ideas or same previous experience??? I hate to trash the mower - it's old as dirt... but body is in good and the engine still runs great.
thanks

[Restrorob]

Can you post the 5 digit model number with the serial number ?

Sounds like a faulty seat safety switch or possible safety switch module.....