I have just obtained a 6 X 18 magnetic chuck. I think the brand is Walker, but I can't tell for sure because the nameplate is missing. The On - Off lever works hard and I was wondering if I should attempt to disassemble the chuck to see if I could fix it. Is this something that can be easily done?
I took mine apart, mainly out of curiosity. It was 8 or 10 years ago, but I don't remember any real problem taking it apart other than magnetic attraction trying to keep it together. The sliding parts are grease lubed and it may be that the grease in yours has dried up and hardened.
It depends on the type of permanent magnet in there. Unless it is one of the modern rare-earth magnets, the assembly acts as a "keeper", and with it apart, the field strength of the permanent magnet will drop significantly, and it will need to be re-polled once it is reassembled.
So -- generally, I would suggest *not* disassembling it unless it is so bad as to be useless.
If you do disassemble it, first lock it onto some object of a known size and measure the force needed to pull it straight off. Then after you have it cleaned and reassembled, repeat the test. This will tell you whether you have lost field strength.
I understand that some places offer the service of re-polling the chucks -- but I have never tried to find someone who will do it, so I don't know what your luck will be.