Broken electric rear window

The rear passenger right hand door electric window mechanism on my 04 freelander has bust. The motor goes OK but various plastic bits seem to have broken such that the window will come down but not up unless I force it by hand. having taken the inner panel off I can see a cable coming out of the top of the motor which seems to be not doing much. So
Do I need to replace the whole unit or is there a simple fix?
Is this easy to replace?
Is there anything special I need to do or know and does anyone know of a cheap source of these things (£95 on ebay)
Thanks Dennis

If you look on E-Bay there are reaplacement cables, but if the plastic guides (at each end of the metal strut) are broken you are probably looking at a complete new regulator unit.
Same happened to me (as usual on a car park in the middle of nowhere set for a family day out)- the window dropped and stayed there. Replaced cable and tried to use resin to fix plastic guide. Lasted a day or so...
Paid £75 for replacement unit from LRC, Congleton, Cheshire (they are on the web). Owner even stayed open late for me to collect part. Great.