32X may emit a strange hissing or whining noise when operating. Certain coils seem more prone to becoming noisy with age.
These replacement coils should help to calm down the unusual sound.
Please see photo regarding soldering locations. Some original coils have 3 legs. The 3rd is a stabilizing leg connected to ground and should not be left open.
Anecdotally, if you have a Sharp voltage regulator at IC13 (large letter S, part number starts with 3) you may want to consider replacing it. The Sharp regulators seem to be more prone to oscillation.
2020-03-24 - Different coil selected with better lead spacing for 32X PCB