I have a small carriage clock that has started to gain about 30 minutes a week. Nothing has changed as to location or treatment! It just started to run fast. It has a platform escapement. I know you can suspect the hairspring, but why would it suddenly change? Any ideas?

Jerry, I would suspect that it needs a COA. It may be running fast due to power loss due to lack of lubrication and dirty pivots.

Curly