I have a Seth Thomas Grandfather clock with three different chimes and chimes at every 15 minutes. The problem is it is chiming 2 hours shorter than the actual time. Example say it is 11:00, it is chiming 9:00.

The next time it chimes multiple times turn the hour hand clockwise until it is pointing at the number of times it gonged. Next take off the dial nut off (make sure to put it in a plastic bag because they can be hard to replace) and turn the minute hand until it chimes signaling 15 minutes after. Now put the minute hand back on pointing to 3 o'clock and replace your dial nut and you are all set.

Fix Clock That Gongs Wrong

Thanks for contacting FixYa.
I wish I had an aswer for you but I dont. Here is a link for a repair man that has an 800 # toll free to call for estimate.
http://clock-repair.net/site-map/seth-thomas-clock-repair/

Best regards. Jewel