I have a cheapo folder I got off eBay. I had the LBS do a tuneup and all was well yesterday when I took it out for a spin. I folded it up and put it in my trunk and this morning when I took it out to go for a ride, the back brakes are too tight and the back wheel can't spin. I don't understand how it was fine yesterday but too tight now. I'm a newbie to all this and I don't really want to go back to the LBS because he was not pleased that I bought a cheapo bike and I don't want to hear his lecture again. I guess this is something I can fix myself, right? But how?