I will asume that you did NOT buy this adapter from marlin crawler, and for doing this you will suffer that fact that the company you bought it from will probly not help you out and fix it. at least marlin would press the brearings in place and back up any problems you might have. and sorry to be negitive but next time spend a little more $$$ and you all wont have to fawk with this kind of stuff and the same goes for the AA gear sets too.
now how to fix. first pull the bearing back out, and go get a new one from toyota. the bearing would normaly be in the case that would support the front output shaft you will see ( at the dealer ) they have an illistrated parts breakdown or the t-case, and there is only one bearing that looks like the mest up one. get a new one. check to make sure there is not abig bur on the in side of the adapter were the bearing would ride if there is debur it with a sharp tool but try not to gowge the aluminum so bad, net put the bearing in the freezer as OPP'S said, and a few hours later pull it out and imediatly put to it in place and push it in. it should push in pretty easy, i would use a socket with a reduced ring around it like a mac socket trying to find one may be hard but find some thing that in no larger than the O.D. of the bearing. if it don'tpush in by hand ( no joke) try the block and hammer and make sure it goes in straight. thats what i would do so take it or leave it
Cliff