Hi! I wouldn't use a grinder or anything which would deposit grit near the piston rings or cylinder wall.You've got to be really careful when you're cleaning without disassembling,because there'll be some particles you can't remove. Use a vacuum sweeper hose before you oil it and reassemble.now if you could block any openings so none of the grinding wheel particles could get into the works,a light dremeling job would probably be o.k.. Here's a trick I use if I'm in a jam and can't get around the problem: Cut a piece of clean shop rag to the size you need to stuff into the area you don't want contaminated. Use enough so the rag will try to expand back out the hole.Now take STP and coat the end of the rag.If you're careful and don't disturb this cloth ,the dirt or particles will not get past the STP into the critical area.When you're done buffing or drilling,just take needle nose pliers and pull thrag back thru the opening and wipe your working area with a clean rag.YOU'RE DONE! Hope this may help somebody. BYE!