had a pain in the a$$ exhaust cover that wouldnt budge no matter how hard u yanked on it & smacked it & finessed it ???? whenever i encounter an exhaust by american cool air corp which is for a hood with anything grease related in the air i break my bawlz just trying to gain access ..... a few years back i mentioned this to the guys at the NYC convention they told me they never heard of this issue but many of my corporate accounts always had these since day 1 & its always been an annoying thing .... its the stupid little round handled ones that use wing nuts to secure it to the threaded rod sticking up .... well if u obtain an account with these i suggest modifying the method of removal such as adding handles of your own because that is now the mission i am on .. i share this info as today i again had one that was a b!tch to break free and even with gloves managed to cut my fingers something nice because i had to reach down under it where all the nice grease is & sharp metal to get a good grasp