Cub Cadet 1517 PTO problem

I'm having a problem trying to find out what is causing my friends Cub Cadet 1517 PTO clutch from kicking off. I've put a new Pto switch on it thinking maybe that was the problem but no luck. I installed a new battery because someone was telling me a weak battery could cause this problem. Could the Pto clutch be bad even though it will engage whenever you pull out the Pto switch? If there is someone that could give me some advice on where or what to check I'd really appreciate it. Thanks

Find out what brand of PTO clutch you have. Use multimeter, set it to Ohms, disconnect wire terminal from the PTO, with PTO at ambient temp (say 70F) read resistance. Normally, Ogura brand will read around 3-Ohms, Warner Electric a little lower 2.5-Ohms or so. While you at it check the 'airgap' setting. Most PTOs have it adjustable, some do not. Check tech specs for your model and verify proper adjustment sequence.