Hello David,
Yes, the 625-only model has everything on the signals chassis. Does not necessarily have to differ so much from the TMB272, which has 3 FM radio channels.
The 625E + 625B + 819B version has the small additional chassis with 3 coil/transformers (and 2 valves) on it.
Also just visible on this photo from the opposite side:
I haven't looked into it in detail yet. I thought to collect any available data first to make things easier. I suppose a full service manual was issued at the time.
It should be possible to restore both sets without any info, but it just makes life easier to have it
I'm glad both TX275s have the EF80s i.s.o. the 6F1s as in the TMB272. I have no spare 6F1s, but exchanging two with each other in the TMB272 resulted in good enough valves for both positions.
In contrast with the TX275s, the LOPT housing of the TMB272 is still in excellent condition:
The deteriorated plastic in the TX275s might have something to do with moisture. Some metal parts are heavily rusted or corroded, so the set will have to be dismantled anyway to gain access to all that.
Jac