So I got a 40kg servo from temu the other day. It is from what I can tell pretty decent quality. All metal gears pretty hefty doesn't feel cheap, but hey what do I know it's my first one buying to upgrade one I've had from a very old Tamiya h1 Hummer. Anyways my receiver, Dumborc x6g I think it's the 6 channel with gyro started beeping Like never before just fast beeps. So I got my other 3 channel redcat that was stock on my car before I upgraded to the Dumbo. Before I go on the servo was acting as if it's were stripped inside and had no power behind turning. I thought first the arm was stripped so I changed to the old one to see and it was doing that same thing so I turned it off then on again and then my receiver wouldn't connect. After switching to old receiver the servo still had 0 torque behind it's arm so I did what anyone does and got a refund, they let me keep the servo and gave me an instant refund. Then I did what anyone else would do and you guessed it took it apart my guess was the rod holding the gear that goes from motor to servo arm wasn't snug in there and allowed it room to wiggle and hence the skipping. Back together it's snug but it will turn 1 direction just fine, turn it the other way it will turn back and forth a few times and stop.
is the pot inside the culprit or am I missing something and anyway the servo could have fried my receiver? Any insight would be awesome. The servo in question is the one I tried to attach but I can't but it's i think a "Woreiuds 40kg digital servo"

if gears are no problem, and only could turn 1 direction, you could check with your PCB ( VR soldering point 3pins or 3wire ), other then that is motor problem. maybe next time you could try SAVOX servo, the quality is better.