Last few days my truck has been cranking slower and slower. I checked the batteries both are good (load tested), I knew my positive battery cables weren't the greatest, replaced them hoping it would correct the problem, it hasn't. Since it's slow cranking and not intermittent start I'm thinking the brushes are worn. has anyone put the brushes from Larry in? Is the soldering very tough (I've done quite a bit of soldering on circuit boards and such), can it be done with just a small soldering iron?