99 explorer 4wd shifting issues...ideas?

[8450]

ive dug around in this for a couple hours and checked some things, but heres whats goin on. had around 6 flashing lights (4wd)in the dash,and 4hi or 4lo never lights in the dash or actually works either. it does engage automatically if you romp on it it gravel. i took the motor off the transfer and jumpered the motor wires and it runs forward and backward. so i cleaned terminals and put it back on. also reset the battery. drove it a few miles. no more flashing. and now the lights in the dash work with the switch between 4hi/4lo. and its actually shifting cause you can noticably hear it click in the switch, then clunk under the truck. i switched it back and forth once about 5 times. then it would not clunk back into 4lo or show the dash light. shut the truck off and back on. redo all that again and it works again until it eventually gets stuck either goin in or out of 4 low. sometimes it goes in rather normal. other times ,the switch from hi to lo(and vice versa) is sluggish,like its struggling to turn the arm. seems to me like the motor has just enough power to engage it or something, which if is the case would probably trigger the code and make it stop working like before. sound right ? i may take the motor apart and clean the brushes and the armature and see if that helps. im thinking theres not really an electrical/computer issue since it does actually work and tries until it quits

 

[8450]

hmm...well ill mess with it myself some more