Couldn't find a post anywhere on web, so did the job and posted a how I did it here.
New Lamp assembly (217 gbp)
4 black plastic anchors
Large flatblade (for removing black plastic pushfits)
Small flatblade (for undoing electrical connectors)
Optional 10mm ratchet spanner
Read all below before job is started, look at alignment of the existing unit. Took about 1.25hrs working carefully and methodically
1. Remove boot floor tray
2. Unclip brush around boot stay
3. Remove rubber bump stop, (unscrew and pull upwards - carefully)
4. Remove black pushfit from back of bumpstop plastic mount
5. Remove 3 pushfits from bottom of hard plastic boot lining
6. Pull up vertically to remove hard plastic lining.
7. Carefully peel back fabric boot lining on side you are replacing
8. Pop off white connector under bump stop mount
8a. Disconnect boot light - it gets really hot!
9. Locate the nuts that hold lamp in place
10. Push off the cable tie
11. Suggestion -using foam bag that new light wrapped in stuff below lowest nut between frame and boot. If you do drop something you have half a chance of getting it back!
12 Loosen the nuts, then can be removed with hand pressure, use bluetak around the edge of the socket to attach nut to socket, then remove.
13 Remove plastic and rubber plug
14 Wiggle out lamp, disconnect
15 Reconnect new lamp
16 Wind on nuts to loosely secure, push in rubber and plastic pin. place shims, then with steady pressure align lamp unit properly. Tighten nuts to secure. Check alignment now. Check all operates as should at this point
17. Rest is reverse of strip down
I did not buy the black plastic pushfits, unlike the older mercs these new ones are not really designed to be re-used and tend to rip off the little anchors when taking them out. Taken out carefully with lots of wiggling, they do sort of fit back in.
Rest of pics in post Replace R172 rear lamp cluster (contd)