Re: 7B92 with no repeating sweep
Good morning Jeff,
I'm chiming in because I've had somewhat similar experience with a 465 which suffered problems with the socketing of the https://w140.com/tekwiki/wiki/155-0049-00 sweep control IC. I found that reseating brought the sweep back - usually. Meaning that the chip was ok and it was the classic old Tek socket issue. I ordered some backups from the auction site and I recall the sellers listing saying that they were recovered from a 7B92. I see in the TekWiki doc that U310 is either a 155-0049-00 or 155-0049-01 based on SN. So your time base has that and is likely socketed.
Also I found https://w140.com/tekwiki/images/5/5d/068-0315-00.pdf very helpful in understanding sweep circuits and diagnosis.
Good luck with it!