Today I noticed my middle blade was actinf foolish by not cutting properly. I would like to know if anyone is having this trouble and how to correct problem. I took blade shaft out completely and looked but could not determine if any thing was wrong. I put a level from eack blade to see if they lined up, they did. Put back together and still same problem, new blades two days ago. I can't figure this thing out, anyone HELP, HELP.