Interesting analog ignition timing circuit

i have this little scooter. Now the weather is getting good I had some plans to drive places with it..

Well, plans.. it stopped working all of the sudden making noises like the cilinder head was hitting the valves.

Then all of the sudden it started working again.

OK. next day: no go, no start . Checked spark: OK. Fuel : well ehh, Checked valves for not being stuck OK. carburator is shit, cannot be opened anymore only with a hacksaw, ordered a new one. While(waiting for part to arrive), thinking.. it could be ignition timing, but it is a potted unit. Those are cheap too, but what is in it that could change TIMING?

So google has the answer to everything, and for sure I found the schematic:

a surprize really, click on the circuit diagram with timing waveforms..

No micro-professor, all with capacitators and resisisters...

Just hope it is not the pickup coil, that is unreachable too (no way to get the screws out except drilling). Should use the thing more often really.... :-)