Pour liberal amounts of 91% isopropyl alcohol and a bit of salt with the piece all in a ziploc, then throw the ziploc it in your microwave for no more than 17 seconds, then shake the hell out of it for about 30s-1min. Rinse with tap water first as its "hard" minerals wash the resin off much quicker, then filtered water to remove the minerals from the tap, which you don't want to smoke. Then, use a toothpick or kebab stick to physically scrape the weakened resin, then rinse with filtered water.
Seriously, isopropyl is quite flammable and can ignite around 20-30 seconds in the microwave, but making it warm enough to not even burn your hands as your shaking makes it so much easier and faster to remove resin. Also, 91-99% iso removes resin much quicker than 70%, so go with the 91% imo for cost efficiency over the 99%, unless you were making some QWISO; in that case, the 99% pulls less chlorophyll and other nasties from the herb/shake/stems, and evaporates much faster due to lack of 9% water and perfumes that the 91% has.
Basically, the iso chemically weakens and breaks down the accumulated "diamond hard" resin, while the toothpick physically scrapes off the now-soft resin.
