The 796D will not process STARS transmissions in a trunked scan mode. In a dedicated bank program all of the STARS frequencies from the appropriate STARS site(s) that you can receive except the primary control channel(s). Do not program the primary data control channel(s). An alternate control channel(s) most of the time is a voice frequency. Do a conventional scan of the the selected bank of STARS frequencies. This method works reasonably will.
Those 25 year old base stations still work pretty good. I hate to think what a pair of tubes cost for the finals. I'm sure there is still a lot of component level repairs done on those things. They were always pretty easy to fix.