Zycomm FM5016 CTCSS Circuit
There is a add-on board which is an obvious retro-fit, as it’s fixed in place by double sided sticky foam.
After some investigation on Google we found that the IC-107 chip was a custom one supplied by an American company called Communication Specialist who discontinued thee type of products
The info comes from a website called Repeater Builder
https://www.repeater-builder.com/com-spec/com-spec-index.html
There were a lot of models of tone generators listed, but after further searching identified it as a SS32 card from the picture on the Repeater Builder web-site
The tone is set by dip-switches:
During Testing, we found that the "Ian" radio did, in fact have a different model of tone generators fitted, we identified it as a TS32 card - once again the info was foundon the Repeater Builder web-site