Keith O - I doubt it would be the switch, although the switches can be figgetty (sp?). Sounds more like your field coil in the PTO is getting to hot and shorting. I think I'd make sure the gap for your disc clearances are good. It's not hard to check, just need a feeler gauge to check the gap as I recall, but follow direction in the Service manual. If the gap checks out ok then it's likely your field coil is going to fail soon. It could also be you're leaking exhaust around the tin muffler box and it's heating up the PTO more than normal, causing the coil to short when it's really hot, so make sure your exhaust is existing in the front, and that your tin work on the engine itself is in place so the air blowing from the flywheel is cooling the head fins and blowing across the muffler box duct mount.
If your coil is failing you used to be able to buy just the replacement field coil and I think one of the sponsors has it. If you buy the whole electric PTO it's pricey. Couple of the sponsors might have a used one or you could post to the wanted section. I'd suggest to start hunting for the replacement now. The whole assembly is a pretty straight forward clutch assembly. When you do replace yours I'd check the bearing (but doubt that would be your current problem) and check the discs to make sure they are clean and not warped up.
Bill J - long time ago someone on here mentioned what an old timer told him "oil is oil, some is better than none". Sounded to me like he'd use just about anything that claimed to be oil. Yes it will work - but how "well" will it work. I see Charles posted about a Simple dealership using nothing but 10w30 in Kohlers. I would not be going back to that place. Can you use straight 40W? Yes, I suppose, and in hotter summer temps like you get in VA I'd think you'd be ok. And yes, I've heard of straight 40W, more often as a racing oil. I wouldn't want to use 10W40 in these old engines unless maybe you're already getting blow by, then it might just help, or it might just burn more oil on you than straight 30W. Please be aware the IH Operator Manual says "Do Not Substitute 10W30 or 10W40" when temps are in the 32degrees or higher range. If I were you I'd just spring for the good 30W stuff, and even go for the low ash type. The older your engine the better you need to care for it. I'd say don't wait for 25-30hours to change the oil - do it at 20hours.
