Simply use your eyes to start with. Locate the plastic connector from the switch to the harness (might be slightly beneath your tank, and above the coils). Disconnect it and unscrew the switch from its housing. Is the plug in tact or evidence of melting?
Using your meter, check the resistance level between the RED/BLK with the key ON. Do the same on the harness side. Also, mentioned earlier, check the large 8-pin plastic connector on the left side of your bike, near the shift lever (this comes from the stator/alternator and heads to the electric panel) for any corrosion. You should check the Ohms of the Y/Y/Y, Wht/Grn wires. (Theres 3 Yellows to check between, a single WHITE and a single GREEN). You're searching for too high an Ohm reading which is an indication of resistance, causing undue heat to build.
You mentioned only getting 13.2 charging. Normally, that might be an issue, but it could also mean that your battery is not requiring more. This could be a case of a very healthy charging system, or it could mean that your Regulator is not sensing properly. But until you solve the fuses blowing, you will need to set that aside.