I have a WC7545 copier that occassionally grabs the wrong size paper when making copies. For example, I put two 8.5x11 sheets in the document feeder and when copied they came out on 8.5x14 legal paper. The trays that are housing 8.5x11 paper are not empty so there doesn't seem to be a reason for this happening. This has been happening randomly for quite some time now. Help???