Have you got a seat base that looks like this?

Not only was the base floppy and not fitting snugly against the leather, the switches didn't operate correctly....a slight poke on the recline button and the seat would keep reclining until it hit the end-stop. The big switch was decidedly floppy as well.

We need to release the remaining fastener at the front of the seat base. There is a small expanding collet around the front of the seat base.....ping this out with a flat-bladed screwdriver:

The seat base can now be moved away from the front of the seat so that access can be made to the switch assembly. The switch assembly is held onto the plastic base with four clips. If you have a floppy switch assembly, remove the two control knobs, these pull away from the base, use two flat-bladed screwdrivers if the knobs are too tight to remove by hand.

Once the knobs are off, the switch assembly can be detached from the clips, two at the top, two at the bottom. The reason for the floppy switches are immediately obvious, although the top clips are OK, the bottom ones have broken at the ends:

The easiest way to get around the broken clip problem is to draw a thin bead of Superglue along the clips and then push the switch assembly back onto the clips. The plastic of the base and the switch assembly work well with Superglue and it was as firm as you like in a few seconds. Push the knobs back on while holding the switch assembly from behind and it is all lovely again.

The seat base wobblyness was due to the upper fixing, this seems a bit weak, and in this case the screw still had a bit of seat base on it when it was removed:

There are a number of ways to fix this, I started with gluing a large washer into the remains of the fixing point:

That was a bit fiddly, especially because a reasonable amount of pressure is put on the fixing. The washer needs to be clamped by the fixing screw to be effective, the problem is getting it into the right place and tightening the screw without putting side pressure on the washer.

I found a better plan was to use one of the 'U' shaped fixings with a self-tapping screw-hole in the middle that are normally used for fixing trim to sheet metal. I glued this in place with two-part Epoxy (Araldite Rapid) also filling up the spaces where the plastic had snapped off and allowed it to set for 30 minutes.

Fit the screw a single turn into the 'U' fixing, clip the 'U' fixing into the broken channel in the seat base and align the seat base in the correct position. Once the seat base is screwed back in place and the lower collet is pushed back in place, the 'U' fixing clamps quite successfully onto the base and all is lovely again:

All done.....time for a cup of tea