Kenwood 4070

Bought this KR4070 off of CL for $20 but it seems to be stuck in AM and it won't switch to any other modes. Any suggestions to a fix? I think it might have something to do with the selection wafers but I'm not sure how to go about replacing those.

My guess is that you're right. The function switch is a series of wafer switches, just like the speaker selector switch. And like the speaker/power selector, there is a rectangular bar which engages the selector and detent mechanism on the front panel and runs through all the sections (stack) of wafer switches. If the link/bar becomes disengaged (and they have - to me personally) the selector switch knob on the front panel will move and snap into place just like it is supposed to but nothing will happen to the wafer switches which actually perform the circuit switching. This is the power/speaker switch mechanism, and the function switch is the same design but with more wafers stacked up: