Please see attached a step by step guides how to replace your window rubbers my van was a 1993 Puck but no doubt it will suffice for all the Eriba models.
It is one of the most common problems that need replacing when the Eriba is advancing in its years and can be very expensive. The Grey rubbers are the worse as they are susceptible to the suns UV and age prematurely. If you can do it yourself it will save you a fortune, it can be done with just a bit of patience .
If I was to give them a spanner rating out of 5 for difficulty they would be as below:

Opening windows 2 out of 5
Side fixed window 3 out of 5
Front bow Window 4 out of 5

This company can supply the rubbers and the tool to put in the locking strip, personally I bought genuine Eriba rubbers from Jandi.

http://www.sealsdirect.co.uk/

Jandi Caravans:
http://www.eribacaravans.co.uk

Have fun!! [bye]