938 was an attempt to be more domestically acceptable. Thorens put their name on it too TD524 - very rare in UK.
938 uses the same motor as the 948. The 938 doesn't have the slide-out cards used on the 948, which allow rapid servicing. The 938 has everything on fixed circuit boards.
The 938 is actually the easiest EMT to change the armboard, I have seen an EMT/SME armboard for sale. I made up a few armboards. You need a 10" arm to fit in there.
However, as already mentioned, EMT turntables are designed as complete units, they are not for fiddling with, and from my experience you are wasting your time trying.
Puresound would, I suspect, have been more positive if he had set his up as EMT intended. I wouldn't say that the price of EMT cartridges is high when you consider some alternatives. Consider the Roksan Shiraz which is a modified EMT.
When I first set up an EMT I was initially underwhelmed!! Well it just plays the record. Don't expect impressive fireworks. High fidelity generally doesn't sound impressive IMHO.
If you buy one, set it up as EMT intended.
I can see that an EMT might not be good for domestic harmony, but you are getting an awful lot for the money - quality turntable, arm, phono stage.
(I have too many turntables, I may sell one of these if you are interested.)
Why would EMT make a direct-drive if their idler was better? Why did so many big Japanese manufacturers make DD not idlers?
In summary, if you buy EMT, go EMT all the way. If you want to fiddle try something else. I have several direct-drives, and I would say that there isn't really anything between them in terms of the motor unit.