I hope someone will be able to point me in the right direction / let me know what could be wrong with 2 watches I own. Not in an effort to cut costs or corners on servicing but because I would like to know what might be the cause before I send them off for overhaul. - itís always good to learn about what makes them tick.

First up I have a Omega flightmaster it keeps great time (within a constant - 15 seconds a day) and has a good power reserve (at least 35 hrs) It has an intermittent fault when the chronograph is run. It occasionally stops the entire watch. I.e. when the chronograph is engaged the watch will run but sometimes the chronograph will stop as will the entire watch. A quick shake and the watch restarts immediately. The watch does not stop if the chrono is not engaged.

Second up I have a PRS82 with the older movement. This no longer runs at all. It has sat untouched in my watch box since March and was running perfectly when I last wore it.
If you shake the watch the rotor spins and you get a stuttering movement of the second hand but for no more than a few seconds. Sometimes the second hand will stutter backwards when shaken. It winds but this does not spark the watch in to life. I am guessing broken mainspring? How it could have broken when sitting untouched in a box in a safe, I do not know.

Many thanks in advance and merry Christmas