[mandh]

I recently picked up a Model 40-190 and found that I could not remove the loctal tubes from their sockets so I could test them. When a little prying with a pair screwdrivers did not work, I found that putting a little light oil or WD-40 on the loctal key did the trick. After the oil flowed into the key, the tubes came out with only hand pressure. When I got the tubes out, it did not look like there was corrosion on the key pin so I guess the oil just reduced the effort needed to remove the tubes.