Hello there, I am using 4% Acrylamide gel on 377 (18g Urea, 5 ml of 40% acrylamide stock, 5 ml of 10x TBE for 50 ml total volume). All of sudden, the gel well was getting more and more unflat as usual. Even worse, the two plates were getting tight and I could not insert the shark teeth comb in for loading. Any suggestions? Thanks a lot David