stole this from another (Altec users) BBS.... thought you guys could help....
http://www.hostboard.com/cgi-bin/ult.../f/3729/t/1771


Can anyone shed some light on JBLs' purpose for using a foam cover on the interior end of the pole vent in a 2245H, in lieu of the more common screen? I am assembling a pair from some E155 baskets and OEM 2245H kits. When I stripped and cleaned the baskets (which both had burnt out coils), only the melted foam where it had been glued to the pole remained. Inspection of an original 2245H through the rear vent screen verified that the foam is installed as a covering for the interior end of the pole vent, just behind the dustcap.
Other than giving an indication that the driver had been overheated at some point, I can see no reason for using foam instead of the standard screen, which they do use on the outer end of the pole vent, unless it's for damping to eliminate 'chuffing' on long excursions. Also I'm concerned that the inevitable deterioration of the foam could cause future problems, by "gumming up" the coil/pole gap. (The lower third of the original burnt coils was black and gummy, with deposits on the pole also).