Welcome to OCC,
If you like great old little tractors, you are in the right place.
The 12 HP gear drive tractors are really great little machines, glad to hear that you found one in such good condition, especially one with so many options.
I agree with Paul about fixing the shifter sooner rather than later, you really don't want to get the little ball on the shifter out of the box (you'll see what I mean by that once you get the shifter off).
Jeff is also correct, ain't nothing like tilling on a gear drive tractor!
Here is some stuff to look at if you have or suspect that you have trunnion problems with your Cub Cadet hydro, start by going here.
http://cubfaq.com/hydrolurch.html
And then here.
http://cubfaq.com/trunionrepair.html
More information here.
http://www.onlycubcadets.net/forum/s...ead.php?t=4635
There is a lot of good debate here.
http://www.onlycubcadets.net/forum/s...ead.php?t=5495
After you have fixed your trunnion your forward-reverse lever and foot pedal may be out of wack, so go here.
http://cubfaq.com/neutraladjust.html