Three of my 3107s and a few friends have the same problem. They all eventually loose power when applied to a workpiece. They will run great with no load, but as soon as load is applied, they bog down and are worse than worthless. I only buy repacements out of need, and they are awsome sanders when they are running right!
It sounds like the bearings are going out, just underneath the Bosch Sander pad. You can take it apart and replace the bearings or replace with a spindle assembly. The part # for the dust fan coupling is 2606610901 and will run about $22.55. The part #'s for the bearings: 2600905058 and 2600905034 and they will run about $11.40 each. It is probably best to do the dust fan coupling because it comes with everything.
Don- ww.toolsandmachinery.com
December 2008
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