This week I started cleaning and re-staffing a pristine 992B using a staff in a bag marked "992B" that was provided for the service by the owner of the watch.

All the 992B parts fit to that staff perfectly; the Balance wheel, roller, safety roller, Hairspring, went on like a charm! BUT the wheel was too short for the watch! After fussing and fretting awhile, I consulted with Chris Abell, telling him that while the staff looked like a 992B friction fit staff, it was TOO SHORT! Chris measured a 992B staff and advised the length was 5.67mm, I measured my staff and saw (to my chagrin) it was only 5.33MM!

So I went into my staff stash and found a Hamilton parts bag of 992B staffs and lo and behold, THEY were 5.67 mm long too!

So what happened? I looked further in my staff stash and a little bag of 992E staffs surfaced like a bubble in the veritable watch parts swamp. Thos 992E staffs LOOK JUST LIKE 992B STAFFS BUT . . . they are ONLY 5.33 MM long.

BEWARE, when you get parts make double sure that you have the correct replacement. These 992E staffs are quite rare as are the 992E model, but they look (to the unaided eye) just like a 992B and BELIEVE ME, you do not want to try to use them in a 992B!

And that would explain why in a Hamilton Factory Parts cabinet there was a special tube that was marked for the 992E movement - only.

Nice work Dave!!!

A few comments from the customer in question:

this is a watch I picked up early last year, which was running great until it fell out of my pocket edge-on to a tile floor. So I went looking for a balance staff.

Quite a few eBay listings and parts sites show Hamilton p/n 607047 as being for the 992B / 950B, and that's what I sent Dave.

The site where I purchased the staff currently has a listing for a "Balance staff for Hamilton 16s #659, long, 5.70mm long, friction, for 950B/E and 992B/E and 4992B IF it is 5.70mm height, nos."

Bottom line, from now on I'll leave the parts sourcing to those better equipped than me to sort through all the misinformation out there

When Dave sends the watch back next week, it'll be sporting a regulator spring from Larry Lamphier, and a better 121 dial from Phil Sanchez. I'll post some photos in a few days.

John, the staff I actually used was in a Hamilton parts bag. To the untrained eye these would look the same. No fault on your part for sure.

Here are a couple of photos of the watch in question (original dial on the right):

one more:

John that rodico smudge on the cystal should wipe right off.