I remember the series well - I used to love it!
As far as I can tell, I think the part you're referring to is this one:
http://www.youtube.com/watch?v=rPKobWMA ... ature=plcpThe scene is at about the 3:30 mark in the video. However, it might not be the scene you were looking for because there were actually quite a few episodes where she was tied up. For a full list of them, have a look at this link here:
http://brianspage.com/query.htmlJust type in what you're looking for and a whole bunch of episodes should come up - then you can hunt them down on youtube or dailymotion or whatever.
Hope that was helpful

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