I use that harness. Your doing it wrong. How are your ribs karted? more detail and you might get some useful advice on using the harness you have.
Hmmmm unless your ribs extend down around your waist I suggest your 'waist' harness is a little on the large size, another possibility is that your waist could be of a larger circumference than your ribs.
Sam has most of the replacement bits for the Power XT at WSS ready to go.
I recently had the same problem and it turned out the bit I needed was part of a "factory recall" replacement thing that North had done for the extension. Take a look at this link (http://www.north-windsurf.com/en/rig-components/Power.XT-FAQ) under "slippage of the rope" and see if you still have the plastic spring in your extension. I replaced and old plastic one with the new metal spring provided by North and it sorted the slippage straight away. I'd already bought the new wheel though which I didn't actually need.
For the rope itself, save yourself some cash and buy the equivalent rope from your local ships chandlers. It seems to work just as well as the North provided rope, just a different colour as far as I can tell.
yeah, the post has been changed. prolly better just to start a new thread dude, but here we are...
so, for the xt, they do provide a tension screw that holds the ratchet down tighter, which is essential for sails with plenty of downhaul like race/slalom oriented sails. i think you just talk to your local and they can organise it for you. don;t know why they didn't just include it in the first place, i think it's a post-production fix.
if however, you've simply broken the rope, well they claim you must use regualtion XT replacement rope, but I've replaced mine twice with normal marine rope...new rope will slip initially until it's softened from water, so I give new rope a good soaking first.
North extension bases, you either love them or hate them. Ive been through 4 of the dam things, each one has something different wrong with them springs, ropes, pulleys,catches. Still, im far to lazy to use anything else.