> Hi all,
>
> Each of my characters is level 10 (2 Knights, 3 Wizard(esse)s, and one Sorceress), but I have difficulty getting through level 4. (All down to 80-50 Hit points)
>
> One of the Wizardesses was originally a Rogue, who I turned into a Sorceress by accident, switched to Knight, and is now a Wizardess. I am thinking about retraining one of the Knights as a Druid, one Wizard into a Knight, and the Sorceress as a Rogue, but it will quite a few more levels to go because I'd like to get the full arsenal of spells first...
>

Keep going!

I think that you are at possibly the most difficult part of the game, because level 4 is far too hard for most parties when they can first get there, but levelling up is a bit boring.

There are really three options for levelling up:-
1) The quickest and easiest is to use the big room on level 2. It's also the most tedious, though.
2) Presumably you have found a set of stairs down from level 3 to level 4. There is money to be made down there!
3) Use the lift to level 4 and see how far you get.
I tend to use a mixture of these options to try to keep the game interesting at this point. Be careful of going down to level 4 and getting killed too often, as running out of money is the worst thing you can do in the game.

In terms of the balance of your party, it looks reasonably OK to me. Personally I'd much rather have sorcerors than wizards, as I think they are far more effective in combat than any other class (including knights) at this stage in the dungeon. I disagree with commie_bat about having three fighters up front, as a wizard is quite robust enough to survive in position 3. I wouldn't recommend retraining anything yet, at least until your spell-casters have a complete set of spells.