So, it sounds like this battery pack might be the answer, or maybe

this battery pack might be the answer?

If the cell layout is correct. The only other thing I would say on the charging theme is that sometimes NiMH may not accept low rates of charge as well as NiCd cells. Does the 7000 fast charge or is it a typical 10 hour trickle charge time??

Given the age of the 7000 I would guess the cell capacities are in the range of 600mAh. If it trickle charges then the charge current will be in the 50-60mA range. You may find that, for some NiMH cells, this current may be below a minimum charge "acceptance" threshold and they may not properly fully charge. For the cells you have pointed out a 60mA current would only be a C/35 charge rate - I would wonder whether this will be enough and I would definitely look for a cell data sheet to confirm their suitability first.

Great stuff. Thanks for all the helpful advice, Puncher.

It looks like the seller isn't far from me - I'm going to try to go and pick them up over the weekend. if he'll go with that. Otherwise, it looks like it will be Monday or Tuesday till they arrive.

Which ones would you go with, link or ?

Update, the seller just got back to me:

Hello
Sorry we do not have any collections, you also have to find out what charge currect your charge gives out as it will not know when to switch off as its a nicad charger and will cook battery pack.

Paul

Hi all, I also have to replace the batteries of my BL 7000. My dealer expects the cost to amount to more than EUR 100. Thus I am very interested in reading your experience with alternative battery packs.

Cheers, js

I've found another pack which looks more hopeful:

linkGo to link, and scroll down to "linkSakura - 5 Cell 6.0v 1000 Mah Receiver Battery Pack (NiCad)".

Any views on this? 

I'm glad you are looking into this Peter as your batteries seem to have deteriorated since you last saw the 7000.
Since you lent it to me it has sat on it's charger 24 hrs a day. Occasionally I would take it off for a play but it would only last 4 or 5 minites.
Yesterday, I took it off and it wouldn't even fire up. It still works fine on the charger though.
Hope you don't think I am in some way to blame.

Andy T.