Hi
The old 40's-50's Benrus watch I got for a song off Ebay is still running like a champ and right on time within seconds per day but the stem appears to need replacing. It occasionally pops out if I'm not real careful and setting the time has become a problem. I don't think its fully disengaging when pulled out for setting causing increasing binding and slippage. There is visible wear and burring.

So far I've found that the Benrus BB4 is the same movement as the ETA 900 movement and the ETA 900 stems are recommended replacement parts.
I just ordered a three pack of NOS ETA 900 replacement stems dirt cheap, still in factory sealed plastic. These aren't trimmed for length and without crown.
I don't know if its possible to remove the crown from the original stem. That crown is unsigned , and images of similar watches and movements suggest these were not branded.

Any suggestions on how to proceed are appreciated.

 

You should be able to take off the crown granted it hasn't been Locktited into place. Place the stem in a pin vise and twist off the crown.

If that doesn't work, measure the crown diameter and order a crown with the same diameter and tube width of the stem.

 

I'd read of stems being dissolved by emersion in a Alum solution, the solution leaving the crown un-affected.
Since the crown thats on it now is un signed, more or less generic, I'm not bothered by the idea of replacing it.
The only Benrus signed crowns I've seen so far were from much later production watches that had two piece stem and crown with male and female fittings similar to the one of my Omega Devile.

Till I looked around I had thought the stem was a poorly fitted replacement , possibly from the wrong brand of watch, but everything looks correct.

I found several of the exact same movements for sale very cheaply in non running condition for parts or repair, but each had a buggered stem , worn out, missing or broken off. These stems must catch HE double hockey sticks over the decades.
Most of the junk movements I found had the exact same dial as my watch, a couple of the dials were in good condition. I may buy one of these to put aside in case i need to replace any internal parts or hands etc.
Since I'll have two extra stems I might repair or have repaired a spare movement and dial as a drop in replacement should this movement fail.
I still can't make out the faintly scratched in service date inside the case back, but it looks no more than a few years old and aside from the problem of the stem which just recently raised its head the watch has given great service, I wear it most every day. Never found a more comfortable watch.
The entire watch inside and out is clean as a pin and the case shows no scratches or any signs of aggressive polishing.
Not bad for less than $18 USD.

 

And you are attaching a picture when?

 

When I get over my present reluctance to dig through a mountain of debris to find my camera and look up the software I'll need for it.
I had a meltdown that destroyed the PC that I'd been using then had to delete all my aps on this one to do a clean re install. I do have the sellers pics saved to documents. Not too bad but a little blurry.
The blurry images are probably why no one else bid on it.

PS
While I had the watch open I took a chance on adjusting out the few seconds per day it gained. I'd rather have a watch run a hair slow than a hair fast since this one doesn't allow for setting the time back even a few seconds.
I had great luck. In a 24 hour test I can't see any measurable gain or loss, not even a second or two. it will take a one week test to be sure of course.

The watch winds easily and I got to thinking that the binding when setting might be due to interference with the winding gear when the watch is already wound tight. normally I always wind the watch fully before setting. I'll wait till I think it needs re setting and the spring has wound down before trying it that way.
The stem will need replacement in any case due to obvious wear and tear.

BTW, I lucked onto that three pack of NOS stems for $6 USD plus $3 USD shipping. Couldn't pass that up. That's less than others charged for a single stem.