Here's the procedure I use:

Both boards: CAREFULLY lift up the VFD along the edge furthest from the pins, and break the stiction of the sticky foam pads. Rotate the display around it's soldered pins and move it out of the way.

Mk2 (flat tabs, surface mount): Wick away as much solder as you can from the pads first using solder braid. For the pad under the IR daughterboard, use extra care and a long-tip soldering iron.

Mk2A (pins, through hole): use a solder sucker to get as much solder off the BACK of the display board first.

Both boards: Using fine electronic flat-blade sidecutters, clip the three pads/pins at the top of the encoder, holding the cutters vertical to the board.

Clip the bottom two, again cutting vertical to the board.

Clip the side earth lug/pad on the side of the encoder nearest the VFD, HORIZONTALLY. Be careful you do not stress the tracking on the display board. Try (gently, when you are sure you have cut through this completely) to lift the rotary, and rotate it away sideways in the direction of the IR board so that the bottom of the encoder is exposed. You should be able to tip it about 45 degrees outwards before coming into contact with the IR board. DON"T FORCE IT ANY FURTHER or you will risk ripping the pads off the PCB - I have seen this a few times and it is NOT EASY TO REPAIR!

Again, cutting horizontally, go under the encoder with the sidecutters and clip through the lug/pad under the daughterboard.

Remove the destroyed encoder.

You should now either wick off remaining solder (Mk2) or solder suck away (Mk2A). On both types this will help you remove the debris of the clipped pins. On the 2A, the clipped lugs of the encoder remain in the large holes through the board. I usually heat these with the iron tip and then push the remains through. BE CAREFUL - the board is more important than the component.

Replacing the encoder is pretty simple: first flux the pads, and place the encoder on the board. Make sure the leads go through the board correctly (Mk2A/green) and are not bent: for the other type (Mk2/blue), make sure the two small locating pips go correctly into the PCB.

Solder the pads/pins first (5 in total). Don't over solder.

Mk2 Only: Solder the exposed earth pad. Using a fine tip iron, go under the IR board and heat the other pad FIRST before inserting solder.

Mk2A only: invert the display and solder both of the side lugs on the PCB. DON'T use too much - only solder the small gap between the lug and the PCB hole.

Before you put it all back together, carefully plug it back into your player to test it. Make sure you get the header on correctly, and that nothing in the display or player can short against each other. If it works OK, power off and then remove it again.

Remove the remains of the previous sticky foam pads from the board and VFD. Using either new, or stacked-up double sided foam tape (to give a height of 3mm), fix the VFD back in place after gently bending it back. Make sure th nipple does not clash with the encoder before you apply FINGER PRESSURE ONLY to seal it back down (Tip: I am now building these up with a 1.5 mm layer of closed cell foam about 2 cm square under the display for extra cushioning).

I would emphasize that if you have already decided to remove the encoder, DON'T try to save it. Destroy it as you get it off to ensure that the tracking on the board is not damaged. Destroy the tracking, and you can say goodbye to the display board - there are plenty of encoders available.

Bear in mind that if you change the encoder, you will also need to change the knob to match the encoder.

Although I see more failures of the SMT (blue) encoder than the pin-through (green), note that the blue ones have been in service for longer.

The blue ones have a "softer" rotary action and a longer "push" than the green ones, and I personally prefer the blue to the green.
_________________________
One of the few remaining Mk1 owners... #00015