So besides regular gear lube changes what other maintenance should I be doing on the drives, couplers, u-joints, and gimbal? and how often?

Check gear lube level
Check water inlet for debris
Check anodes if eroded
Lube prop shaft
Touch-up drive paint
Check connection of gimbal ring to steering shaft
Lube driveshaft U-joints
Lube tailstock input and output
Check bellows
Check gimbal bearing

Check the plastic wear strips on each side of the drive that contact the gimbal ring flanges...they,ll sometimes come up missing.

If you have HP transom assy's, keep an eye on the fasteners that hold in the hinge pins, I've seen those break.

Check the torque on the gimbal ring u-bolt clamp periodically

all of these require drive removal correct? how often do you do them, the only one I don't understand is the steering one? are you talking about the steering arm that connects to the brazil valve with a pin behind the motor?

Do the pins the gimbal ring pivots on need any maintenance, how do you tell when they are worn out. it seems like one drive wiggles more than the other when I tug on it.

The HP transom assemblies have stainless hinge pins that are held into the gimbal ring by 2 10-32 screws on the earlier units and
by 4 1/4 bolts on the later units .

On the earlier units, keep an eye on the screw heads, I had one side of mine break off both heads and the hinge pin starter to walk out.

A friend of mine had the 4 bolt arrangement and had a pin break under the pin head, you could look inside the threaded portion of the pin and
see where it separated from the head.

The helmets have fiber bushings that are pressed in to them, they take the wear, not the pin, there are also phenolic washers on each inner side
of the gimbal ring that provides a wear surface between the gimbal and the helmet...they can come up missing.

Another thing that can happen is the upper swivel shaft,( that is not made of stainless) will start to rust and knock out the seal in the transom assy ,
this will let water in and eventually knock out the swivel shaft bushing, allowing some wobble.

I really haven't had any problems with the lower swivel pin and bushing.

The gimbal ring shouldn't have more than .010" of vertical movement between it and the transom assy.

The best thing you can do is make shure the the gimbal clamp u-bolts remain tight, and do like your already doing and grab a hold of the
drive and see if you have any excessive movement and if so, where it's coming from