Wheel Bearings Problem - Help Requested

[Segal]

Problem with right front of 90 9020v wheel area.  Frequent but intermittent
sound from 

wheel area . . . sound like whup whup and sound goes away when press brake
and when 

move steering wheel off center to one side.  Mechanic replaced axle and
wheel bearings.  

Sound went away for about a week and came back.  He replaced bearings and
sound went 

away for a few days and came back.  Mechanic has no idea whats going on and
believes 

that the bearings are fine, axle is fine, and hub is fine.  Since he cannot
find the cause, he 

now is suggesting it is the transmission.  Please HELP.

 

Rich