I have an old steel frame (road bike, as it happens).
I have been using external BBs. This is the second drive side cup which has worn loose.
Not sure whether it is simply aluminium cup being worn down by stell shell (and therefore whether a steel shell would fare better) or else frame needs facing.

It’s a 1983 Holdsworth 531 frame if that helps

any advice, thanks

Plastic spacers by any chance? They don’t seem to fare very well against the thinner wall of the BB shell that you often have on a steel frame, may be worth swapping them to metal ones, won’t do any harm to have the frame faced too.