i doubt it, tbh it sounds like the switch, its essentially two switches in one so down can work fine but up not at all if the contact is poor, the mechanism is a cable on a spool, if it slips then it's fubar'd.
if it is your mechanism, i guess it could be caught on the up but unravel on the down, i've bought 3 of these now and they've been excellent every time, oem parts are near £200!
http://cgi.ebay.co.uk/RENAULT-CLIO-ELECTRIC-MOTOR-WINDOW-REGULATOR-98-05_W0QQitemZ280274071643QQcmdZViewItem?hash=item280274071643&_trkparms=72%3A1301|39%3A1|66%3A2|65%3A12|240%3A1308&_trksid=p3911.c0.m14