Thanks to you both for the comments.
Ruffinit - you're right, I've only loaded a film and fired a couple of shots - I have not put a full roll through to see that happens, neither have I developed the previous 'dodgy' roll.
I tend to agree with your thoughts on throwing out things which probably just need a bit of attention. I try to look after four cars aged 11 - 15 year old for myself and offspring (generally considered old in UK, I think more of you guys in the US look after your vehicles for longer than we do over here, it's very much a 'disposable' way of life) and I would not just trash the ME S without looking at things more closely.
I've recently made the mistake of of buying 5 non-functioning (seller described them as 'shutter not firing, cosmetically either 'good' or 'very good') Pentax bodies with the intention of trying to learn how these things work - take em apart, find the problem and put them back together (better to do it on a known faulty body than play about with a working item!).
The fact that I have paid just 15 uk pounds including postage for a Program plus, P30, P30T, P50 and a Super A really reinforces your point. After installing batteries and pushing all the buttons, it appears that all but the Super A actually work. I won't be certain until I put a roll of film through them, but it seems some of us are happier to get rid of things rather than check things out fully.
Erik's a bit too far to go helping me out though