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« on: June 17, 2014, 10:02:07 am »
It is hard to guess from your explanation as to where the actual problem may be. One of the more common problems and easiest fixes is blade slippage in the clamps. You might try taking our the set screws and thumb screws on both the upper and lower clamps, clean the ends off with a little rubbing alcohol and then lightly sanding the ends with 220 or higher grit sandpaper. When reinstalling make certain the set screw comes out to be flush with the interior side of the clamp or maybe even a quarter turn past flush - check your manual to see if it has a recommendation. Most blades come with a light coating of oil which can ultimately transfer to the set and thumb screws and cause slippage while sawing. When opening a new set of blades I always dip the ends in rubbing alcohol and towel dry them and then when ready to use have a piece of 220 grit sandpaper I rub across the ends before inserting in the clamps. This is probably the most simple fix if it works. If it does work you might even think about taking out the set screw and putting some blue LocTite on it to avoid the set screw turning.
If that does not help, the next thing to look at would be your clamps and thumb screws to see if by over tightening you may have stripped the threads slightly on either the thumb screw or the thumb screw side of the clamp. If so, you might need a new clamp of clamps or a new thumb screw or thumb screws. If you do fret work the most likely culprit here would be the one you loosen and tighten most depending on whether you top feed or bottom feed.
If the problem is actually in the tension adjustment lever it gets more complicated. You might Google for Rick's Scroll Saw Site (I think that is the name) as it has some good tips on tuning up DW788s and Excalibur Scroll Saws that might apply to your problem.
Hope this helps.