Are these made out of "Bakelite " a hard plastic ? if so there might be a seam around the circumference . I would place a little WDxx or similar product there and let it soak in a while and then try to open them up. The material is very suseptible to expanding and contracting.  Often someone tightens them up and then over time they contract and really lock up.   You cold also try using a hairdryer to heat up the earpieces this may soften up any gunk that may be present in the threads.....

    Check out google.com search "830s measures"  A guy named Richard Measures has a pretty good article on hints re the 830s , no output is one of the areas covered,   if you caNT FIND it send me your address and i will forward it to you, n3bif

     Greetings,  I am looking for a fix to keep my computer from causing interference in my hf rig, a ts 520s, if the rig type matters.  It seems that on 10-15 I have no problem on 20 a little and then progressively worse on 40 80 and 160, so much so that i have to shut it off when i am on the air. the noise is just low grade hash but it will pretty much knock out any thing on 80 and 160 and is uncomfortable on 20 and 40, it has a steady presence so i feel it is not AC, also it is the pc itself not the monitor , i have nothing else in the system other than the pc's harddrive  and a cd drive but the noise is present with out the cd drive driving, the computer is scratch built with i believe an amd processor. The computer is about 3-4 feet away from the rig and everything is grounded but removing the ground shows no increase in the noise, any ideas ? thanks , i would like to use the logging program etc while on the air for obviuos reasons,

     its possible that the knob stem is bent ,not much you can do to straighten it, if the knob drags though as it rotates sometimes by loosening it and pulling it out the shaft a bit, keeps it from rubbing the face plate...

     1.   hold the main knob and rotate the silver fine tune knob til it reads correctly, real hi tech huh ?
     3. The self-described lumpiness may be from a bent knob shaft, mine is slight and noticable but not to the extent you mention, there are two screws at odd angles to each other remove these and the knob will come off and you can check the "trueness" of the shaft
     ?.   I assume you mean the plastic flip knob, you can remove the face plate (the Service manual gives excellent guidance on how to do this) you may be able to "borrow" the plastic piece from one of the other switches, I would suggest the grey heater switch , i never turn this off, so just put it in the on positoin and leave it there take the flip part and swap out the broken one,
         Good luck  Dave