1988 Oldsmobile Cutlass instrment panel, mechanical speedo,

I have replaced the lite switch, I have the dash apart, the bulbs are ok, I get voltage out from the dash dimmer switch on the yellow wire. I move the slider and the test lite varies in brightness like it should, I probed all of the contacts in the dash blocks and do not find any voltage from the dimmer to any contacts on the blocks. The fuse (#4) is good. Courtesy lights work off the dash dimmer, emergency and all self test lights (oil,temp,battery etc), turn signal and bright indicator lights work, but I can't see my speedo or fuel gauge etc at night. also, daytime radio dial light works until I turn on park or head lights, then it goes out
thx
Paul