It arrived today. It's a little nicked up on the outside (handle, edges, etc.) but otherwise pretty clean. It's the /AF model with the optional external ref, and most important to me, a later model with the updated Ohms board - no AA batteries! Internal date codes seem to indicate the latter half of 1980.
I put the shorting bars on the correct binding posts, and did a quick check. ACV looks pretty good from < 0.1V up to about 12V - the highest AC output I had readily available. It tracked my semi-calibrated Heath IG5218 meter (the signal source) pretty nicely over 3 decades. Auto/manual ranging seems to be OK.
DCV is a bit weird - it's like the measurement is divided by 2 and offset by a volt or so. 0V input reads about -1V and 10V reads about 6V. Other than that it seems to track input voltage monotonically. No discontinuities or random garbage, just the wrong values. Seems to do the same on auto or manual ranging. The zero cal pot has no effect.
Ohms is just wacky: Open circuit seems to give the all-segments-on overload indication reliably after I worked the range switches a few times (cleaning probably needed). Putting a 2.2K resistor or higher gives that same 5K reading; connecting a 220 gives me about 90 or 9K, depending on how it feels at the moment. Short circuit gives OL on the 200 range, and a steady 0.95, or 9.5, or 950, as you move UP toward higher ranges - yes, the dp moves to the right instead of the left. Auto gives the 0.95 reading. Almost like it's not scaling, but thinks it is.
I checked the PSU and the ±18V and 13V supplies were correct (haven't looked at the waveform to see if they're clean DC). The +35 reads +25 and the -35 reads -37. Someone has clearly replaced C20-21 with caps of unknown provenance, but C18-19 are the dreaded original Spragues. C22 had the brand "Brasileira" written on it but if it was replaced, it certainly was done well - the joints look professional.
So, I think all the PSU electrolytics probably need to go, and the Tantalums as well - correct? Is it worth looking at anything else until that's taken care of? I haven't been able to locate a schematic of the newer Ohms board - all the manuals I've seen show the old one with the AA batteries. That board seems to have something broken, though it has no obvious visible defects.
Edit - found the 8810A manual which appears to have the new ohms board schematic.