taking apart the turntable is fairly easy. just turn it upside down, and take out almost every screw you can see, plus the foot pads (which are screwed on to the base). pull back the entire rubber casing, taking care not to tug on the power/audio/ground wires which thread through a hole.
cabinet and tonearm schematics
you can get to the pop up lamp assembly from here. take out the holding screws and there's a screw for the side guide post, plus screws that hold part of the cylinder together. by design, the standard light doesn't fit through (from the bottom) so you have to take this all apart to get it in there.
[ see alternate directions below to avoid disassembling the spring chamber ]
the difficult part for some is getting the metal clip out. the metal clip keeps the spring in place is difficult to deal with. the spring is what makes the light rise up. once the clip is free the spring, the light can come out. my clip was metal and wedged in there (some are plastic / believe replacements are plastic). once free, the spring flew out. i thought about this later, thinking you could remove the screws first and take it apart that way (from the top) -- but i probably won't have to do this again for a while to test that out.
anyway, this is a poor design, at least in terms of servicing. by bending the metal clip, i got the light out. i broke part of the clip in the process, fortunately there was enough of it left to hold once i put it back together.
the tricky part is getting the new light, soldered with wires traveling through the cylinder (so the light can move properly) and through the hole. i had to cut the existing wires and solder them in place. screwed up placement of the wires, so i had to cut and resolder them each time i realized the wires were misplaced. so you might consider paying more attention than i did when you first get the thing apart, so you know how it all fits together.
it was a pain to put it all back - and a one point i was clumsy enough to have the spring fall into the platter assembly. great. so i had to take that apart to get the spring out. i wasn't sure how to do that as first but it's actually really really easy. (just lift the platter off - mine was stuck and needed some tapping on - then again, remove all the screws you can find).
i didn't stop there, because i didn't see the spring immediately, so i took the boards and the motor out ~ everything in pieces ~ and yes, finally the spring. i suppose the upshot from taking the entire thing apart is that i feel better about using equipment ~ at least how it fits together. i had previously tinkered inside, adjusting the metal clip-spring in the tonearm assembly - but replacing the pop-up light was certainly more involved and a good experience. the local shop estimated the labor for that at $60. if you're not handy with a screw driver and a soldering iron, it's probably worth the money.
ok, so ~ i thought along the way their might be a way to go change the light "from above"... check out these instructions as an alternative. the trick is to cut and resolder the connection at the top. that way you don't have to disassemble the spring chamber. smart. but either method works. well, unless you're sloppy with soldering. i think you could also *thread* the wire through and solder that way. and if your spring's retaining clip is pliable, well that'd be a fine way to go.
http://www.djdepot.com/replacing_stylus_light_technics_1200.html
http://www.geocities.com/SunsetStrip/ Venue/1193/HowTo_ReplaceStylusLight.htm