My rear pulley is not opening up.I have just gotten this bike back I had it stored hours away for the past three years.The rear pulley was always crusty.I think I remember putting a red spring behind it.I forget what usually causes it to not open up .I know I have to pull it off and look for myself,but like I said it's been a while .Can anybody give me any suggestions as what to look for,or what to do to fix this?