2004 Transfercase Counterweight Missing

[Patch]

I have a 2004 sporttrac. 4x4, Automatic, 4.0. Not much in the way of modifications . A few days ago it made a noise that sounded like an airplane propeller was under the truck. That noise has since stopped and as of yet has not returned. It has also since stopped shifting into 4 wheel drive. I climbed under it to check u joints and found my transfercase counterweight was missing and appears to have been gone for a while. My question is how much damage could that cause? Should I replace the shift motor and install a counterweight or replace the entire transfer case?

 

[DILLARD000]

While TCase CounterWeight is somewhat less critical & being without it may or may not cause a vibration,
if it was loose & fell off, then a good chance other items are loose\failing or need attention as well.
Have you ever BottomedOut or HighCentered the vehicle & possibly damaged CounterWeight+ShiftMotor?
Inspect underside & entire vehicle generally; look for worn\bent\broken\missing\corroded\leaking parts & hardware: nuts, bolts, brackets, suspension components... Check fluid level in TCase at upper fill plug; use only MerconLV compatible fluid; needs to be drained+renewed every 33kMiles\4years.

Set EBrake & chock Wheels, then remove 4x4ShiftMotor (4 bolts) & use ViceGrips to manually rotate shift stem 2WHi~4WHi~4WLo & back, to confirm if TransferCase & other 4x4 mechanicals are operable.
If TCase mechanicly still works, then likely have a failed\damaged 4x4 ShiftMotor or ControlModule.
Best to briefly exercise TCase thru all 3 positions, once a month, to keep ShiftMotor from getting stove up
& provide some confidence that it will work when really needed.

 

[Patch]

The amount of dirt in the bolt holes indicates it didn't just fall off but has been missing for at least 2 years possibly more.
I have checked suspension parts. In the last year, I've replaced Upper and lower ball joints passenger and driver sides, cv joint on the front of the transfer case, tie rod ends passenger and driver side.
No corrosion. Perks of being in Arizona .
The skid plate that covers the transfer case would protect it from high centering and banging into things. A visible inspection of the transfer case didn't reveal and leaks or visible damage. The only thing recently that could have damaged the motor is a water crossing.
I have yet to verify that I can manually shift the transfer case. I will after Christmas.