Another P/S question

[compoobah at valleyimplants.com]

Whilst waiding through the IRISes power supply, I found another exploded paper cap. (PS date 1985).
 Is this likely normal, or should I look somewhere else (don't have a working scope). Would the failure of one cap put more stress on the remaining ones?
 When I get the machine working, I hope to have something interesting to report, but I have no confirmation yet.

 ScottQ