Post the Sears 917.xxxxxx number so one can look at the correct schematic.

A few upper case letters and paragraphs would make your post easier to read and understand. Your call.

I'm guessing here, but usually when the PTO is blowing fuses something is pulling too many amps.

Which lead me to two things Bad elect. clutch or wiring to the elect. clutch chafed and shorting out against metal part. Or bearings in deck hard to turn causing the elect. clutch to pull too many amps trying to stay locked up?

Probably need to see if the pulleys turn easily and disconnect the elect. clutch. If it don't blow fuses then you may have narrowed it down to the elect. clutch or elect clutch wiring.

Sometimes elec. clutch can be adjusted, but I dought that the problem???

Probably is a short in the PTO circuits as suggested by rc.
And as bill pointed out, without the full technical model number of the machine we can't know what the wiring diagram looks like because we don't even know which model to search for.
Most likely the fuse actually blows when you engage the PTO (because the engine does not typically need a good fuse to KEEP running once it has been started).
But this thread has the scent of a one hit wonder so we might never know.