Billy D.,
Be patient, you will get the 108 up to par if you are persistent. It doesn't sound like there is all that much wrong with it.
I bought my first cub(128) for about what you paid for yours. It ran ok, but after close inspection, it needed a lot of work.
I figured if I were to have something dependable, I might as well go all the way with it.
My case was a little different than yours. My cub was intended just for gardening, so I had some time to play with.
After about a year, it was finally complete. Unlike your case, I had several issues with my tractor and decided to replace anything I considered a possible problem in the future. I also stripped down every part, primed, painted, and put it all back together.
This extra work cost me more, but in the long run it will pay off. The total cost of everything with me doing all the work was around two grand. Just remember, this was a total overhaul, so your case should be much less expensive.
Either way, this is cheaper than a new one which will not last near as long as what we have!
Speaking of a money pit, let me tell you about my motorcycle. Only one word: Thousands!!
Hang in there, it will be well worth it.