I used to hang around the Lotus distributorship in New Orleans when they were port of import for the central section of the country. Europas would sometimes bake in the hot, humid New Orleans weather for a long time before they were sold. The clutches would always stick, and the "official" remedy was glb's method. Sometimes the wrench that worked there would have to drive it around the block to break it loose, but if you jerk it a bit, it will come loose.
Back in 1980, I had Dave Bean build me a BDA and I thought I was going to have the same problem when I finally got in on the road (almost twenty years later, he whispered), but I didn't. I don't know if it was the flywheel and clutch Dave used (the flywheel is aluminum with steel friction surface. I think he got them from Tilton) or because the motor was inside the garage that whole time. Or maybe I was just lucky!