** checked the vent for any clogs... lint as far as I could reach **
Unless you cleaned the absolute complete vent, what you did may not enough I'm afraid.
** Could there be a clog of lint past the place I can reach and thus need cleaning or unclogging by my apartment manager? **
That would be my guess.
** the lint was damp not drenching but indeed moist **
That will likely be because the moist air isn't being properly vented.
** it is in an apartment **
Than call the apartment maintenance to *thoroughly* clean the venting as it is a fire hazard operating it with even a partially plugged vent.
!-> Discontinue use until it can be corrected.
** April or May of this year a new heating element was put on so that can't be it? **
A failed heater element most often results in no heat at all but poor venting could lead to the premature failure of that element and may have been at least partially responsible for that previous failure.