Try using a lubricant along the guide edge. There are special spray lubricants and wax sticks made for this purpose but a thin coating of Vaseline or aerosol cooking oil will work fine. Another thing to try is to not hold the trimmer against the edge too hard and make sure it is in forward cutting motion when it is in contact with the edge. These precautions should eliminate any bearing burn or marring.
For an in depth discussion of the craft of working with plastic laminate, I recommend a book I wrote on the subject called Making Plastic Laminate Countertops. It is published by The Taunton Press and available from their web site www.taunton.com. Signed copies are also available from me (drop me an e-mail for details). For continuing discussion about working laminate, refacing cabinets and more conventional kitchen remodeling subjects, I publish a newsletter called Professional Kitchen Craftsman.
Good luck with your next laminate project.
Herrick Kimball Editor-PKC newsletter PO Box 1117 Moravia, NY 13118 (315) 497-9618 email@example.com