Dewalt DW988 side handle replacement

[my02explorer]

The threads on the bolt that holds the side handle together on my Dewalt DW988 drill have stripped, and I can no longer tighten the handle. Any place I have found selling replacement parts sells only the entire handle assembly, for around $15 (plus shipping). All I really need to replace is the 6.0mm x 1.0mm, 110mm long bolt. But the only place I can find such a bolt is

and the head is too small, allowing the bolt to turn when tightening the handle. The original bolt head appears to be 12mm wide.

I also tried a 1/4x20 4-1/2" bolt and nut, but the nut doesn't fit properly inside the handle, and can fall out when losening the handle.

I'm reluctant to replace the entire assembly, when most of the one I have isn't broken. I also don't want to replace it with another Dewalt assembly, since I was able to strip the original by HAND tightening it.

Any suggestions as to where I can find a replacement bolt?