2002 Lincoln LS transmission

I have a 2002 Lincoln LSE with a 5 speed tiptronic transmission. I put it in reverse the other day, and it started to fight a bit. It does not roll backwards on its own, but does after a little gas is applied. Also, when in neutral, it still rolls forward a bit. Feels fine when in drive. I know I have to take it into a transmission shop for repair, but the problem is I know nothing about transmissions. They could tell me my hornswazzle went bad, and the whole transmission needs replacing, and I would be none the wiser. Does anyone know if this is a signal that the transmission needs total rebuild, or is it a simpler solution?

Thanks. Any info is appreciated.

Todd