Help with Zenith M730
 

I am working on an AM/FM/AFC Zenith M730 from around 1965. I have replaced the selenium rectifier and the paper and electrolytic caps. It sounds good, but I am still having one problem with the FM. The FM drops out repeatedly. What is odd is that if I switch to AM and then back to FM, the signal returns, until it drops out again. I am guessing that there is a problem with the band switch itself. I was wondering if anyone has seen this before or has any suggestions on troubleshooting the problem. Thanks.

Spray the band switch with deoxit or other good control cleaner. After 40 years, these switches become dirty and cause the exact same problem you described. Probably would also be a good idea to clean the tube sockets with deoxit. Let everything dry and it will probably work fine.

Thanks for the suggestion. That's what I suspected, as I fixed a scratchy volume control on another radio by cleaning it, but wasn't sure about this one.

Update: That was the problem. Cleaned it up and working well now. Thanks again.