When the factory tuners die, thus far it seems to always have been due to a failure inside the RF module. The RF modules are available from Patrick, and can be fitted to rejuvenate a factory tuner. Not cheap -- the parts & repair cost arount $75-$90 or so.

If you don't get any better offers, I'll give $20 for the dead tuner -- I have an RF module here that I might install into it for (yet another) spare unit..

Cheers