The Program + came back, but it still read low - but at least it was consistently so. I was told by the repairman that was all he could do and that he could adjust it no more.
My cure? It seems if I have ASA 200 film in it, if I set it for 400 and the meter is bang-on. I was at a family event and my brother-in-law with his K-1000, my friend with his SuperProgram and my P3n metered the scene exactly the same with the same given the same subject matter, so I played with the settings until the meter read "right".
It's been giving me great shots ever since.