Broken off windage adjustment knob on No.1 Mk.III - options?

I just picked up a 1913 BSA No.1 Mk.III (no star - which surprised me, seeming the volley sights have been removed and the forend replaced, maybe when the barrel was replaced in 1922). The windage adjustment has been locked in place on the rear sight leaf by someone using a punch. This is all well and good, but some monkey decided to try and adjust windage and broke the knob off (not me, I hasten to add). I was wondering what my options may be, besides replacing the rear sight leaf completely (I would like to keep the numbers matching as much as possible). I was thinking of having the thread drilled out, and modify another adjusting knob (cut most of the threaded part off, and having the rest of the threaded portion turned down to fit the hole), then using epoxy to fit the adjusting knob in place. It would only be cosmetic, but as the adjusting thread can't be turned now anyway, any fix would only be cosmetic. Anyone else have experience of this problem and ways to fix it?

Usually the adjustment is locked in place with a cross pin in the middle of the sight base platform thingy. I'd think you could do a non-functioning repair fairly easily.

Spinecracker, I am fairly conversant with the SMLE adjustable sight and have disassembled several for repair. First, remove the rear sight from the rifle. Lock the sight up snug in a padded vise with the bottom of the sight facing upward towards you. You will quickly spot the windage adjustment screw. Get out your Dremel tool and cut the screw in two on both sides of the sight leaf. Separate sight from sight leaf. Remove old windage screw from sight base, even if you got to dog it out. You are now ready to reassemble your nonfunctional sight that'll look correct.

Now, my real advice. Personally, I'd be very inclined to hunt up a replacement windage sight off eBay where they still show up for sale with some frequency. Pay your money and replace the whole unit and be damned. Truth told, about half the SMLE's out there got a mismatched rear sight assembly. Who cares if the serial number is the mismatched so long as it is the correct sight? At some stage, it obviously did not seem to bother the Brits.

If the mismatched serial number bugs you...you can always get the replacement sight renumbered to match. Recommend "Engraving by Angela". Angela will do you a first class job and will replicate the font and size to match your old part at nominal cost. She's on the net and is located in Texas. Or just remove all of the old serial numbers by polishing them off. I've seen a number of these with ALL of the markings removed, ready for a new number. That's the way they might have been issued as field replacements back in the day.

OR---you could throw caution to the wind and disassemble the replacment sight and attach its components to your original sight. Anyway you do it, it' gonna cost some cash so get used to the idea. Ya know whatcha gotta do to make it right for the next generation, huh?

Good luck!

A few photos of a crosspinned windage adjustable sight:

https://www.milsurps.com/images/impo...DSCF0929-1.jpg

https://www.milsurps.com/images/impo...DSCF0928-1.jpg

https://www.milsurps.com/images/impo...SCF09291-1.jpg
Won't help the repair process, but just to clarify the issue for those that haven't encountered it before.

I need to sort out photos, but the rear sight I have is not pinned. Someone used a punch to dent the top of the rear sight in the region of the screw in several places to deform the threads and hence stop it from being moved. Looking at jmoore's photos, all I may need to do is clean up the metal where the knob was broken off with a Dremel, then reblue and weather the parts to match the rest. If so, then all I need is a cut off to put this rifle back the way it was between the wars (last year stamp on the buttsocket behind the safety is '36). I would love to know where this rifle has been, as there is no "sold out of service" mark.

Edit - I might have tried just drilling out the broken thread portion if I could find just the adjusting knob and screwthread, but I think they only turn up on complete rear sights lol.

Finally got a replacement rear sight leaf with a working windage adjustment, and it even has BSA and Enfield inspector markings like my rifle. It was a little tricky working out how to get the elevation slider off of the old sight (it had some crud in it that prevented me from depressing the button on the side far enough), but all is now sorted. I will try and sneak off to the range on Saturday to do a range report. As for the 1941 Long Branch that I have been restoring, it is all done (woohoo!). It was test fired yesterday and, apart from a little work on the sear, it is good to go.