Yes - the flower nail was one of the best tips I read on this site! Especially for my bigger cakes. I use the nail, bake strips and 325 for longer...
(I started baking at lower temps as a rule anyway b/c my OLD oven usually ran around 50 degrees too hot...it was an apartment stove and it was before I started baking for family and friends, so it was just MY cakes/cookies that got ruined
... then I found this site, and realized that many of you recommend that for "perfect" cakes anyway!!!
Hope you figure out the problem - don't give up yet!!! Good Luck!!!!