The electric window on my 607 was going up quite slowly, i took out the regulator/mechanism and noticed one of the plastic guides has partially broken and presumably putting the window out of alignment making it slow to go up.
I see repair kits on ebay but has anyone done a 607 regulator repair before, i want to know how to slacken the window cables while changing the broken part?
this looks really similar to my 405 window regulator, I've never rebuilt one, simply changed them complete.
On that the cables have an end, similar to a bicycle brake cable or handbrake cable, that pops out really easily, shown behind the 'main bit' close to the motor itself, on your top pic. Turn it over & have a look see if your 607 one's similar.
Also check that you do indeed have to take the broken plastic guide doofer off entirely, or whether the fitting will accommodate the cable without needing to do so