: I SENT MY SEAMASTER 300 FOR SERVICE AND ITS STILL 5 SECONDS FAST. I
: WOULD LIKE TO REGULATE IT MYSELF. DOES THE "SCREWBALL"
: CASE OPENER WORK WELL WITH THIS WATCH AND WHAT SIZE SCREWDRIVER
: DOES ONE NEED FOR THE REGULATOR SCREW I APPRECIATE ANY FEEDBACK
Not to be contrary here on your sudden want to self regulate an expensive vintage watch, but 5 seconds fast per day on a 50 year old watch is just incredible timekeeping. No way would I open that watch up and fiddle with the movement to try to get better results. One wrong movement by you could permanently damage it, not to mention the other stuff mentioned by Jim. If you want to practice on something, pick up a vintage bulova or something under $100 and familiarize yourself with the workings, etc. I would hate to see you ruin such a fine watch. "What size screwdriver?" I shudder at the thought.