Hi Julian,
I'd sent this in PM, but thought I'd stick it here as well, just in case any of us are in the same boat again.
From your description of slack wires I'd say one of three things may have occurred;
#1. The tensioner wire has snapped. Unlikely but it does happen, and you'll need to make a replacement.
#2. The center slider block broke/split. This has happened on both my windows, and is a fiddly but DIY fix.
#3. The spool mechanism has burst open. Again unlikely but I've just had it happen.
So first step is strip down the door (good write up
http://www.charliex.net/door.htm), and get the window motor (which you know works) and also the wire and "bow" (slider channel) pieces. This will test your patience, but everything will slide out the front speaker hole eventually, and once you've done it the first time it gets much quicker the 2nd and 3rd times.
Then, if #1. read here
http://lotuselancentral.com/forum/viewtopic.php?t=7937 (ah, see you've started there already!)
If #2. buy the following part numbers:
Window Butterfly - A100B6271S
Centre Slide for Window Regulator (Left Door) - A100B6211S
Centre Slide for Window Regulator (Right Door) - A100B6210S
and read here
http://lotuselancentral.com/forum/viewtopic.php?t=7635 for my own tale of woe and suffering Smile
if #3. read here
http://lotuselancentral.com/forum/viewtopic.php?t=8610&start=20 where I even included pictures!
If all else fails, post some details of what you find when you get the parts out and we'll all see what advice we can sling your way.
Cheers,
Ian
Ford Fiesta Mk2, VW Polo, Golf GTi, Lotus Elan, Honda Accord Coupe V6.
Calypso Red Cali #7683 - Bought at 29,000 miles, and sold at 75,000miles.