My GE GDT655SSJ2SS Dishwasher was plagued with the grey steam vent cap constantly falling off. It is a screw on piece of plastic that will pop off if over tightened with the as supplied equipment. I purchased a new cap and seal for the steam vent. The new screw on cap was of no benefit. The seal I purchase is about 1/4" thick. Today I replaced the seal, the old one was in good shape but it is about 3/8" thick. This keeps the screw on cap from engaging more thread. When I put the thinner seal in, the threads were able to come thru the interior panel and allowed full thread engagement and a well tighted cap. The seal is sufficiently compressed. The root cause if you have a steam vent cap constantly falling off, is the interior seal is too thick, you must replace.

That requires removing the door which is not to hard if you find a youtube video of anyone removing the door. The videos fail to show accurate info if you have the model number I have. The video suggests you can easily remove 1 screw, pull a hinge out, remove one more screw and pull the panel off. On my dishwasher, the hinge cannot be removed until the inner panel is out of the way. If you are only trying to access the inside to replace the seal, the hinge removal was an unnecessary step. So for mine, once the door was removed, there is one screw holding the hinge to the bottom of the inner panel and two screws on the side holding the hinge in place. Both screws must be removed on both side to allow the inner panel to be slid to top side unlocking it from the outer panel. It does NOT come straight out as some videos suggest. Do not remove the hinges for this task, slide panel and this is a very simple job.