I own an 1800 series Cub Cadet with Hydrostat. Just recently, while mowing, I noticed a pulsating feeling in the "gas" pedal. A few weeks prior, when going up hill, the drive belts would make a squealing sound. Now, my questions are: Could this "pulsation in the pedal" be a drive belt issue? Could this be a transmission issue? Or could this be as simple as replacing the fluid in the tranny? Any help will be appreciated! Thank you.

I would check my belts first.
If okay replace the filter and fluid,
If this doesn't help might look at the charge pump on the hydrostat.
Luck