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I had a problem with Rose. The end button started to rub my neck, just felt odd. I tried changing the shoulder rest which worked for a while, but then the button would again punch my neck. I finally looked and saw that the button was tilted up and working itself out of its hole. Which was also the reason that I had to re-tune it so often. I took it apart, cleaned up the hole, packed some sawdust and glue in, used three sizes of drill bits and a file to re-create the cone shape and put it back together. It worked. Then suddenly it all came apart as the tailpiece strap stripped its threads and slammed down. I put on a new strap and all is well now. I am assuming that the strap was being stripped one thread at a time which caused the button to tilt as the pressure was released and regained. As I have been changing strings often and doing other adjustments, I probably have aggravated the situation.
edit:hmm, guess I was wrong. Had to retune this morning. My button is getting loose again. Blah.
I believe that usually end pins are fitted using the same tools (namely a tapered reamer and a peg shaver) as used for fitting tuning pegs. The two would set you back a minimum of about $70. It's a good investment if you plan to ever do more than one peg job.
For the reamer, I was able to substitute a 6 mm steel rod wrapped helically with a triangular piece of paper and then with sandpaper. You could probably use a 1/4" wood dowel such as soundpost stock instead of the rod. By varying the dimensions of the triangle, you can adjust the taper to match that of whatever end pin you are going to use. You would need calipers to measure the taper of the pin, and sandpaper to adjust its taper.
If your end pin is long and has a uniform taper, you can wrap the end pin itself in sandpaper in order to form the hole.
Of course you want to avoid making the hole bigger than needed. If the hole gets too big, you would need to plug it precisely and redrill it.