I was under the impression that Chaplain's assistant was migrating to an NCO only MOS.
Probably to keep some of the riff raff down. No idea why, but I think I have only met one Chaplain assistant with a good moral compass. I have known 5 others that have stolen from collections, went AWOL, multiple ART-15's, etc.
So unless you piced up E-5 it may be dead in the water. Either way I would go see your Badge Wearing Career Counselor. It will not be an easy process, unless you are going into the Reserves or National Guard.
They used to do that type of thing (balanced to balanced, or understrength to understrength) in 2006-20010 or so, when the Army would hold on to anyone.
Its pretty common now to let you only go into an understrength, but my info won't be as current as the Career Counselor's so hear it from them and please keep the forum posted.