Yes mate, getting it off the truck is more of a ball ache than fixing it :lol:
take off the fair-lead, remove the tie bars (22) and pull it apart, careful not to lose the rollers which sit in the grooves of the brake assy(11) inside the drum which might fall out (sit them back in the grooves to reassemble), you'll see the floating gear (7) at the gearbox end, and the mashed retaining ring (8) usually held on by two small +drive screws to the main gear, it'll have pulled through those screws leaving them still in the main gear.
Now you could just replace the retaining ring and pop it back together, but depending how old/how much abuse it's had, you might want to change the nylon bearings (21) too. I did the bearings, retaining ring, and got new boots/covers for the electrical connectors (that had melted) for about £20.
If it's really minging inside you might want to take the flanges off the motor or gearbox to clean inside, if so you'll need new paper gaskets too to reassemble it, mine was spotless inside.
If you pull at an angle all the rope bunches up at one end, this forces the drum into the retaining ring (as you found!)
