Get a soft-faced hammer and a brass flat-nosed punch (about 3/32 or 1/8 inch nose). Drive the sight out of the dovetail slot..... IMPORTANT !!!!! drive the sight out of the slot from left to right, not right to left. Then, get a dovetail filler (most any shooting supply outfit should have one) and drive it in from the right side until it is approximately centered in the dovetail. The filler will prevent any ding from bending over the lip of the dovetail, and it just generally looks better, anyhow.