开云体育

Well here is my first actual contribution to the group. I had to learn the hard way what most of you probably already know--NEVER REMOVE THE KNOBS FROM A 2200 SERIES SCOPE UNLESS YOU ABSOLUTELY HAVE TO.

I figured it would be easier to clean the front panel with the knobs removed (and it is) but I have experienced about a 50% breakage rate when removing the small knobs along the top and for the trigger. They are old and brittle. As has been pointed out, they are hard to find and not cheap when you do find them (although I was fortunate enough to talk a guy on eBay into selling me a lot of them for a pretty reasonable price).

So, I have been experimenting with ways to rescue the broken ones. What generally happens is one side of the little plastic retainer clip on the inside snaps off. One thing I have tried is drilling out an HP knob that looks exactly the same and figuring out how to secure it (these are available by the bushel for cheap at a local surplus store). No luck on that so far, but that is for another time.

What does mostly work is cutting a little piece of plastic tubing in the shape of the missing piece and sliding it into position with tweezers. It works best if the clip is completely broken off flush, but that is rare, so you have to cut the tubing to account for what ever part of the clip remains. The tubing I use is the flexible, clear plastic polyethylene Tygon type with an OD of 5/16in and a wall thickness of 1/64in.

They seem to pop back on pretty well. There is ever so slight an eccentricity when they turn but you'd really have to know what you were looking for to notice it.

I think it might even work better if the entire clip was missing and you might try removing it with a small grinding tool. Trying to break off the clip or remaining pieces has resulted in complete destruction of the knob. Let me know if you come up with any improvements or better ways to rescue a knob.



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