I think the threads in the downtube are a bit busted, so the downtube shifter screw got loose when using the lever. Yep, I'm using a busted SIS 6/7speed Shimano 600 downtube shifter in friction mode, since the cassette is 8 speed.

I would like to put a different downtube shifter, but since this one works, I don't see a point. Are there any indexed alternatives for 8 speed for downtube? Or 8speed means STI. Btw Ultegra 8 speed STI is too expensive, if I could find one... Of course if I stumble upon a friction only set of 600's I might put them on