It's an early amp, in the #0030'-0040 range.
Adrian put the upgraded transformer inside, as the original Mercury Magnetics units proved to be total crap.
we are working on it today to bring it up to the latest specifications.
Here's the first expression of dissatisfaction with the ill-fated reverb transformer, but why worry? Bruce is working on the amp that very day.
Naively perhaps I took this as an indication that the work could be done in the sort of timescale I'd previously imagined.
So I left it a couple of weeks before wondering how they were getting on - see part 31.