It may be worth mentioning that the Lens is not glass but Polycarbonate/Plastic-dont put any kind of solvent or anything scratchy near them! Some have mentioned using Toothpaste!
Get underneath and slacken off the adjuster,you'll have to remove a heatshield first. The brake shoes tend to catch in a groove that has been worn into the drum part. You can slacken off the one side at a time through the little hole in the drum/disc assembly. Trouble is knowing which direction to go! Its a right pain in the backend. Far easier to slacken off as suggested,underneath where the cable splits in two,that way you are doing both sides at a time.
I had same problem on a front caliper. by removing the outer pad and dropping the caliper back over the disk I was able to pump the piston out a bit further. Plenty of silicon grease under the rubber boot on the piston surface and then used a Ford rotary retractor to squeeze and twist the piston back in. I did this a couple of times to lubricate and free up the piston. HTH.
Please be aware that which ever direction works for one side will be the opposite for the other side! I 'think' it is up on drivers side and down on other side. The so called toothed wheel you are working on actually has rounded cut outs as opposed to straight like a cog or gear wheel.
If you are trying to adjust Handbrake travel then you are working on the wrong adjusters! You should be under the car working on the handbrake adjuster which is just before where the cable divides to each side.
watch you dont break the plastic cruise connector like what I did! Unable to replace same 'cause I still cant get the bloody throttle connector of. :-/
Wondering if a bit of gentle heat will expand it enough to come of?