EITHER INCUMBENT City Council member Steve Minn is getting nervous about the race for his 12th Ward seat or his lawn signs are becoming a collector's item. About a month ago, Minn claimed that at least 50 of his lawn signs had been stolen. At that time, he attributed the thefts to "kids playing pranks" and members of "the 2-1 Click," a group of white, teenage gangsta wannabes headquartered in his ward. Now, he says, more signs have disappeared and he's shifted the blame onto political rivals. Recently, Minn sent out a letter to his staunch supporters saying that "we have lost almost 20 percent of our 500 lawn signs in the last two weeks to purposeful vandalism... Our opponent's [DFL endorsee Karen Wilson's] signs are not suffering the same fate--you draw your own conclusions." Just in case constituents failed to draw the proper conclusions, the letter ends: "Consider sending a contribution in the enclosed envelope..."