Removing knobs advice?

[Smidge204]

I'm seeing if I can repair a sticky select switch on a Hitachi V-1565 scope. Feels like there's some sort of grease or something inside that's dried up.

In order to get at the switch I need to take the frame apart, at least partially, which means getting the printed plastic control label card off to get at some screws behind it, which means pulling the knobs off.

They are on SUPER tight, and since the scope is otherwise in perfect working condition I'd like to not wreck the thing. Only two of the knobs (Volts/Div selectors) have setscrews. A few of the knobs have plastic tubes that reach further back and those slide right off. Most of them, though, feel like they're glued on.

Any advice for removing these things without damaging anything? Or maybe there's a less direct way to "heal" the gooey switch? I can't see the actual switch body.

Here's some photos!

http://www.smidgeindustriesltd.com/scope01.jpg
http://www.smidgeindustriesltd.com/scope02.jpg

[langwadt]

I'm seeing if I can repair a sticky select switch on a Hitachi V-1565 scope. Feels like there's some sort of grease or something inside that's dried up.

In order to get at the switch I need to take the frame apart, at least partially, which means getting the printed plastic control label card off to get at some screws behind it, which means pulling the knobs off.

They are on SUPER tight, and since the scope is otherwise in perfect working condition I'd like to not wreck the thing. Only two of the knobs (Volts/Div selectors) have setscrews. A few of the knobs have plastic tubes that reach further back and those slide right off. Most of them, though, feel like they're glued on.

Any advice for removing these things without damaging anything? Or maybe there's a less direct way to "heal" the gooey switch? I can't see the actual switch body.

Here's some photos!

http://www.smidgeindustriesltd.com/scope01.jpg
http://www.smidgeindustriesltd.com/scope02.jpg

some knobs have a removable end cap with a nut/screw behind it

[Smidge204]

I hadn't considered that, but looking at the knobs very carefully with a flashlight and magnifier they all appear to be single piece molded plastic! 

[Fraser]

A classic and gentle method to remove knobs is to take a fabric or silk ribbon, wrap it once around the shaft so the the ends are set at each side of the knob. Pull the ribbon tails and the pulling force is gently applied to the fragile knob.

Other methods involved proper knob pullers that look a little like a simple IC puller. U shaped metal with a claw at the ends to catch under the knob. Not to be used on knobs with skirts ! ...why? You are sure to rip the skirt off in chunks!

Plastic straps that slip behind the knob and are levered against the panel have also been used but I never found them to work well.

Metal levers may be used if appropriate padding is used. Cardboard works well.

Always check that a knob is not a collet type with hidden screw or nut under a knob cap. The number of times I have seen abused knobs and broken shafts because people mistook a collet knob for a simple push on type. Those collets grip very well !

There is often an adhesive foil tape used on splined knobs to improve knob grip. This can make removal harder.

Fraser

[Smidge204]

A classic and gentle method to remove knobs is to take a fabric or silk ribbon, wrap it once around the shaft so the the ends are set at each side of the knob. Pull the ribbon tails and the pulling force is gently applied to the fragile knob.

That did it! All I had readily available was some plastic ribbon but it did the trick wonderfully. Almost effortless.

Many many thanks! Hopefully the rest of the repair attempt goes as smoothly!