Tuner misalignment - how to fix

Hi

I've recently bought a vintage Pioneer TX-8500II tuner and whilst it all lights up and sounds good, the tuner dial is slightly misaligned. In other words, on channels where I know the FM frequency , the dial pointer on the display is in the wrong place by around cm.

Correspondingly, it means that at one end of the FM dial, the pointer goes way to the end (the high number end) whereas it won't go quite all the way down on the pointer to 88.0 FM

I've had a fiddle inside and have established where the issue is. Attached is a photo of the cogs with turn the tuner. The metal cog has a start and end (it isn't perfectly circular so that it would just keep going round). What this means is at one end where the metal,cog comes to an end, the dial doesn't get the its end point.

Logically the answer is simple - if I could,only shift the cog by 2 or 3 teeth it would go that bit further. But I'm worried about pulling the large spool off and unscrewing anything in case I lose or mess up,the string that moves all the bits.

Tips please?

Thanks