When I was molding parts for ful scale aviation, we used Freecoat, I think it was number 77?
It worked very well. However one thing I discovered, with every mold I made, the first several parts were typically a BEAR to get out, upon further investigation from those in the know and years of experience, apparantly, the first several parts help to finish cure the mold and until that time, the parts are fairly hard to get out. In your case, the only thing not cured would be your finish system. Perhaps some prolonged exposure to higher temps would help, and I LOVED the freecoat mold release, was reliable, easy to apply, and worked well for me