I am pleased to report that careening was indeed a fairly simple and painless process as others have mentioned on this forum.
I have managed to remove the CB, and tomorrow I plan to replace the uphaul and hopefully find a fresh line suitable to replace the downhaul. I have some witness lines pulled through the CB trunk so that feeding the new lines back through should be fairly easy, although I suspect getting the CB pivot bolt back in may be frustrating but we will see.
A couple of curious things, the CB had water sloshing around in it! About half way up in the middle on one side there is a small hole, by moving the CB around I could drain most of the water out of it... but why is there a hole there, seems a bit odd. If it was for draining I would expect it to be closer to the leading edge, should I block it up? There is also a sort of square indent at the top of the CB on the port side adjacent to the pivot, but it doesnt seem to serve any purpose. If anyone knows what it is I would be interested to know, below is an image of the CB with the odd square depression.
For anyone interested how I careened my DS II step-by-step, this may be useful.
Your mileage may vary depending on your trailer type.
1. Position the boat where you want to careen, allow for about 40% of a boat length behind the trailer. Remove the boom but leave the stays attached.
2. Chock the trailer wheels from the rear and raise the hitch end as far as possible,
3. Loosen the trailer strap and go to the rear of the trailer.
4. If your trailer is like mine with rollers and bunks a determined pull on the transom will start sliding the boat backwards off the trailer.
5. After pulling the boat back around 40% boat length the weight of the boat will just about start tipping the trailer up.
6. Position a tyre or something soft a couple of feet further back and then slide the boat even further back and rest the bottom of the transom on the tyre.
7. At this point the trailer hitch will be up in the air with the bow on the trailer and the transom resting on the ground, but everything should still be stable.
8. Position another tyre under the hull but at or close to the end of the trailer to support the bow when it finally comes off.
9. From the hitch end of the trailer start pulling with a little wiggle and as the boat is almost off the trailer you can raise the hitch end even further and gently lower the bow onto the tyre. I had a little help here to steady the boat but didnt really need it.
10. Position some soft things (I used pool noodles and a small bathroom carpet) to the side of the boat.
11. Haul down on the main halyard to start rolling her on her side and make certain your soft things are going to protect the side of the hull as you lay it over.
12. After getting her about 2/3 of the way over it will be very easy to pull down the rest of the way, and then just secure the mast to something heavy to prevent her from trying to right.