The problem is the arm fits into a gimball or bearing in it's base which holds it firmly. Well it doesn't hold firm anymore, the arm moves nearly a centimetre on it's base. It still sounds OK, but obviously is not a stable platform for a cartridge.
I should have said, I live in the UK.
TW make mounting plates for any arm, on request. Finding another Ortofon would obviate the cost of having to buy the new plate. It's a good arm, I think Jelco made it for Ortofon. The Distributor for Ortofon is only 10 miles from me, but they say they can not try to repair it.