My clutch pads were also glazed, sanded them a few times, but it didn't last long before the scoot started shaking at take of and low speeds. Bought a new clutch and it was ok again. I think that you will have to do the same. How many miles on the scoot?
Never heard anybody use boric acid...
5500. I sanded the other one a bit and have had no issues since ~5k miles since then. Had to deglaze the bell a bit at the time as well.
In some respects glazing is normal, but some riders tend to it more than others. The bike in questions is predominantly ridden by my wife who's easier on take off's than I am so the pads spend more time in the friction zone per say.
I was told a trick that seems to have got it for now; although since I have the time laid out for it and it ain't that hard on the SYM I may take it apart and look it over anyway to see what really happened there. I'm not sure if the trick would deglaze a blued bell properly, or just do the pads. If the later I question it's longevity a bit.
The trick was to hold ones brakes and rev it up and hold it a bit. Make sure you have room in front of you and do wear gear in case ya slip and take off kinda abruptly.