Darmah Front Forks Problem/Fix

[peaky]

I have a 78 Darmah with 24K miles. I noticed the right front fork was acting strangely while powering through a right sweeper. Since it was time to change the fork oil, I decided to remove them both to check the travel. Ceriani forks. Found that the piston at the top of the stem that bolts to the bottom slider was completely stuck in the fork tube! Took a mallet, a dowel, and a couple of whacks to free it!

The piston looks to be made of pot metal. It was scored and had stress cracks (not from my whacks). I took it to a friend of mine who is going to machine me a replacement set out of aluminum. He is going to include a Dacron ring to help with fit/slide. Guy was a naval air mechanic so he knows his business.

Any ideas on what would cause the forks to bind? I'd hit no bumps. Anyone interested in a set of pistons? He said they would run $30 a set.