2005 Cub Cadet Volunteer 4x4 - low speed

[NLB7928]

I have a 2005 Cub Cadet Volunteer 4x4 we've had since new.  I'm sure it used to go 25 mph.  Now, it's maxed at 15mph.

2 years ago I changed the belt and the rear end oil.  The driven clutch looks like it opens all the way and snaps back as it should.  The 4x4 and the diff lock both seem to work fine.

I cleaned the drive clutch and that allowed us to shift again.  I removed the cover and sprayed brake cleaner and air into it (blindly), without pulling the clutch.  We had been shutting it off to switch between F & R because the clutch wouldn't disengage.

It also makes a high pitched whine at top speed.

I'm pretty sure it's gotta be one (or both of the clutches)...but they're kinda salty to just throw parts at it.

Also, anybody know where I can get an aftermarket clutch that might not be $650?

Thanks,
Nathan