Sky Quad LNB versions

Quick question, I have identified this afternoon that my quad LNB has failed -- vertical channels (high or low band) are not working when the receiver has been live for more than a few minutes despite the fact that the receiver is outputting the correct 13/18V switched signal.

I don't want to pay $ky £65, and am quite happy to replace the LNB myself (I've put up motorised systems in the past) but I've not kept up with the details on the fittings of the minidishes so am not sure which LNB is the correct one to buy.

I *think* that my dish/LNB combo is a MK3, and it looks as if this means that I could buy a cheap (<£10) MK4 LNB plus adaptor to replace the current quad. It's a Skyware SX-719QS/S. What bothers me is that this has been installed for a while (probably about 7 years) so it may be an earlier version, I'm not sure.

Am I right or do I need something else?

Or you could just tell Sky you're gonna leave and they'll do it for nowt (as long as you agree to another 12 months of service).

I did think of that, but the problem is that I got the box 6 months ago on a self-install basis. So the box is covered but the dish isn't, and I'm contracted for another six months, so I'm over a barrel really.

You don't need to agree to another 12 month minimum contract, they'll just do the repair for nothing if they think they are going to lose you.

EDIT:
Just seen your comment about already being contracted for another 6 months...which does make a difference, of course!

I've just decided to buy the LNB and be done with it....

It's only a fiver from ebay and if it won't fit, well, a new dish is still only a tenner on top of that.

No way am I paying Sky a big pile of fivers to tell me what I already know!