if you melted the velcro, you werent using too much pressure, the speed was set too high. im just guessing here, because when you apply too much pressure, the machine stops moving. like i said, you want 10-15lbs of pressure when using the pc, pull out a scale and see how much it is. i want to say that the pc stops rotating at 20lbs of pressure, but i might be off by a bit. there is no such thing as applying too much pressure with the pc. try making a black mark on the top side of your pad, setting it at speed 5, wetting your pad with some qd, and set it on your car. keep adding pressure, at a certain point, the black mark will just be moving back and forth, not even an inch.
you want to let the pad and product do the work, but in order for the product to do the work, it needs to be broken down. pull out a scale, and find out how much pressure 10-15lbs is. i tend to watch the black mark i made, and i can remember how fast it needs to move in order to have at least 10lbs of pressure on it. if youre applying less than that, several things could happen. for one, you could up the speed past 5, which in many cases can cause pad/backing plate failure. you could think that you need a more aggressive compound/pad because a light cutting/polishing pad isnt working. if you use a abrasive cut, with a cutting pad on the pc, you could cause micro marring/hazing due to the fact that it doesnt have the speed to break down the product correctly.
correct technique is everything. if you would like ill post a picture of my buddies saab 900t that ive done recently with my pc. i started off with a rotary, but realized that it wasnt neccessary...so i stepped it down a bit. still need to finish up the front driverside door when he comes back on wednesday since he needed the car for work. it was marred slightly by a medium cut. but for the most part, he was happy.
oh. and the amount of time that you need to work in a compound/polish differs from product to product. you basically need to find a sweet spot between when it goes clear, and when it starts to dry.