Thanks for giving it a try.

On the sale, I think I will say No. If I were going to go to all the trouble of sourcing some new RAM for the IIfx, I would want to get RAM that I knew for sure was unproblematic; plus, as I say, I have reasons to keep it as a System 6 machine anyway.

It is, however, possible that the problem lies with the 1MB SIMMS you are trying these with....