Thanks for your interest.
I'm not going to embed every image I took because that might be overwhelming, so I'll link to the whole album at the end.
So here is where I started, the turntable with the dust cover and headshell removed.
I took apart the tone arm "tower", not sure what else to call it, which was a bit of a trick because of the tamper-resistant screws. They look like Spanner "snake eyes" pattern but they're not, or perhaps they're metric. Anyway, I got them off with some minor scratching using the tips of snap ring pliers.
The internal lever that lifts the tone arm was made of some sort of alloy, and either corrosion or moisture caused it to expand, crack, and wedge itself in the pivot mechanism so it stopped working. It also made it so the lever crumbled apart when I removed it. Here's what's left:
Not much useable here - except perhaps in figuring out the shape of what I need to recreate.
Here's a view down into the inside of the tone arm tower:
On the right are the uprights that support the axle that the broken lever pivots on. On the left is the tone arm, set aside.
I need to make a new lever but the old one is a puzzle of crumbled pieces. So I can use the points of reference in the tone arm tower to estimate the dimensions I need. I make a "story pole" out of a toothpick and mark the pushrod hole, the axle/pivot position, and the edge of the opening where the lever ends flush with the outside of the tower:
It sounds like I know what I'm doing but I'm really just making this up as I go along.
I take the story pole and the leftover pieces of the old lever and sketch out what I think the new lever needs to look like. I cut out a rough blank from a piece of 1" x 1/4" aluminum bar stock I got from the hardware store. Crude work, since I'm limited to hand tools like a hacksaw.
I use a grinding wheel, a dremel with a flexible attachment, and some needle files and spend about an hour shaping the new part:
I reinstalled the pushrod so I can test the fit and the action:
I install the new lever with the axle:
At this point I have to put the tone arm and the tone arm bearings back in, test the action, and then pull it all back apart and file down parts of the lever that aren't fitting or moving right. This was really tedious. It was also tough at times to figure out where the lever was hitting the tone arm or the tower shell because when you have the arm in place, you can barely see the arm at all. I probably put it back in and pulled it back out to tweak the shape a dozen times or so.
Here is the final shape:
It's not perfect. I removed too much material from the lower "nose", which is the part to the right in the picture above, so there is a gap between the lever and the base of the openening in the arm tower. There is also a gap to the left and right because the metal stock I used was only 1/4" wide and the opening is about 1cm. But considering the turntable was unusable on a shelf before I got it, I think my goal of functionality over cosmetics is acceptable.
There is a washer on the right side to reduce some "play" in the action because I filed down the part of the lever that sits between the pivot uprights a little too much. It doesn't look too bad, I don't think.
Here is the turntable reassembled and with the lift action adjusted. It works properly now, and that makes me really happy.
Next will be adjusting the arm balance, replacing the cartridge with something that hasn't been sitting for 20 years, etc. Right now it makes noise, but it doesn't sound very good.
Here's the rest of the photo album for those who are interested:http://www.flickr.com/photos/14714378@N ... 696757808/
Thanks for reading!