The EMI M400 build quality has been discussed many times. It is fair to say that 'as built' they were not well contructed for many reasons. They are usually out of jig and seem to have been constructed from ignorance.. Any and multiples of the following normally applies: main frame skewed, keyboard tight and difficult to remove/replace, pads offset to either right or left, capstan not parallel, key depth suspect, under powered motors, unshielded transformer etc.etc.. The good thing is that it can all be put right but with a lot of effort. Macca has the last two EMIs built and they were honest to goodness crap. A predigious customer but that mattered not a jot to the ham fisted lads at EMI.
Best,
Martin