I suggest you read the threads found in the link below to see if any of the dialogue in them fits your situation.
Hint, did you possibly reverse polarity wit the battery or with jumper cables at any time during your work?
The thread contains a second link inside it to yet another older thread on the subject.

Here is a link that might be useful: round ana round ana round we go

Mownie stepped up with some great advice.
IF the diode is external AND shorted.....

IF the above fails-
You don't have to trace EVERY wire.
Just the Red wire from the PTO switch to the electric clutch.

Actually I did initially reverse the battery when I installed it. It was set up opposite of my last one. Could that damage something that I should replace?

Thanks for the help.

Looks like i need to find that diode.

Batteries have a + mark and a -mark which should always be noted as to where the posts are oriented in respect to where they NEED to be when the battery is in place in the machine (and when buying the battery).
Many batteries are offered in 2 versions (or part numbers).
Batteries having an R suffix letter in the part number are the SAME as a battery without the R in all respects EXCEPT that the cable post positions (orientation) are Reversed.
I hope this helps someone sometime when buying a battery and they encounter an R in the part number.
I should mention that exposing these types of electrical systems to a reversed battery polarity event often destroys the voltage regulator (or a rectifier diode as the case may be).
That may be checked using various tests, volt meter being a good one.
Check battery voltage (using volt meter) with engine off, record the reading.
Start engine and open the throttle until the engine is running at governed RPM. Check battery voltage again while engine is running. The voltage reading should have risen to a value of somewhere near 14 volts or a bit higher, or it should at least be INCREASING to a higher voltage that what you read with engine off.
Symptoms of not charging will range from a battery too weak to crank engine.............to having the PTO clutch not engage or even "drop out" of operation when you mowing.

This post was edited by mownie on Sat, Jun 22, 13 at 11:58