Hello everyone, new member here! I've got a pretty early (serial num. 1800; mfg. mid/late 1984) Tandy 1000 original that seems to be having some sort of problem in the memory department... Whenever I turn the unit on, it throws up some errors that seem to change whenever I hit the reset button. Now, my best guess is some sort of memory fault, but not the chips themselves because I've played the swapping game with the existing memory chips and nothing changes. Is there some sort of memory controller chip I can test to see if that might be the problem? I'm not super experienced with electronics like this (I usually work on 1920s-60s radios & 1940s-80s TVs). Let me know if any additional information would be helpful. Any help would be appreciated, thanks!

Below is an example of the type of errors it throws up
(and yes, I turned down the TVs brightness on the flyback side since this photo was taken)

Vid Addr: Base: BBE8h Off: 004Eh
Data Fault: Written: FFFFh Read: FFF7h