Getting the things apart can sometimes be difficult, you'll sometimes find the edge of the back is outside the edge of the front, halfway round, and then the edge of the back is INSIDE the edge of the front for the rest of the distance. I have a set of blue handled soldering aid tools, one of which is sharpened like a woodchisel, I find it the best tool for levering the things apart. You don't insert the tool in the gap at right angles to the surface, you use it parallel to the surfaces you are trying to separate. If you are unlucky you might break off a tab, but one tab mightn't matter. When you get it all apart, you'll probably find that there's an oilly deposit across the pushbutton contacts and maybe other places as well. The oil comes out of the rubber in the button membrane. I use Palmolive dishwashing liquid detergent (green) in much diluted form, and a 1 or 2" paintbrush. Immerse the membrane and brush it over in all directions, then rinse under the tap. Then wash the PC board the same way. Don't use too much brush pressure. When thoroughly dried, inspect for any remaining oilly patches and perform localised cleaning the same way if there are any. Water will go under any surface mounted chips so thorough drying is ESSENTIAL. Particularly inspect the painted "fingers" of the fixed contacts to make sure that the two "hands" of "fingers" have clearance between them. If necessary you can use a sharp bamboo skewer to scrape the gaps. The coating of carbon paint actually flattens out to make the fingers wider, causing clearance to be lost. Check the battery contacts for corrosion and clean as necessary. Eroded contacts can be scraped and tinned with solder. Any that you're not happy about might be patched up with contacts from your junkpile. If the contacts have been corroded, after dealing with them, coat with a film of oil. If the job is for someone else, tell them to keep the battery contacts oilled.
The contact repair paint (silver) seemed to be the best repair for the ones that don't work, the surface must be free of oil for it to stay. Any open PC tracks can be linked across with a FLEXIBLE bypass wire, sometimes you need to get some distance away from the break to find something to which you can solder, also you can use a single strand of wire across a break, and glue the wire to the broken track with the silver conductive paint. Don't use SHORT links as when the board flexes they will come away. I've had controls where I've had to add 20 links! Sometimes I drilled holes and put the links on the other side of the board. Then there are the controls which have all carbon tracks, and sometimes they cross paths. It all depends on how hard it is to buy a replacement, whether you go to this much trouble.
It's better than getting up from your armchair to push a button on the TV itself..... The generic replacement controls invariably have some functions unavailable, so best if the original can be fixed. Having a light touch when using the buttons (from new) makes a HUGE difference to the life of the contacts. I didn't have much luck with the carbon paint when used on the contacts. It came off gradually. But it was useable on tracks. Sometimes the quartz crystals would fail - some were 455KHz, you could check the remote using an AM transistor radio off station. I have an infrared remote control receiver from an old AKAI VS4 VCR under the shelf above my bench, with a BNC lead to the CRO for checking.
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