C8.25 backlash adjusters not moving

Regearing an 8.25 to 4.56. attempting to set backlash. Problem is the threaded adjusters do not want to turn with the bearing caps on. 99 FSM makes no mention of what to do with the caps until step 4 when it tells you to torque them down to 70 ft/lbs. I've tried just putting the caps on loosely and just snugging the bolts down, that works, but seems like it allows to much free play to be accurate as the caps are not all the way down against the housing. threads are lubed, and adjusters are in straight. will proceed with what works, but wanted to see if anyone had the same problem or had any ideas. thanks
Ryan

the bearing caps need to be slightly loose to adjust backlash. if not they would work loose while driving normally