"I not only replaced the one that had blown, but also the other two similar sized caps that had not. I felt while I had the PSU naked, I might as well do the lot, especially as I had the parts.
The larger 0.22uf one there is also likely to go at some stage. However, I had no spares on hand so that one was spared the indignity of replacement...for now (-:."
Well the day has come...
This was the most spectacular I've seen yet. Lots of smoke with extensive damage to the cap.
This 0.22uf cap is now replaced and the Kaypro II is up and running again.