I just went thru the same thing with my 55 2nd. When I disassembled everything last winter it was so worn out that all the pieces came out easily. Reassembly with all new parts was considerably harder. I finally had to resort to following the repair manual TO THE LETTER. Everything went together correctly on this 4th attempt. The first 3 tries had scuffed up my new paint on the window frame. Now I have that to touch up, but the window and vent look and operate like new. Good luck.