According to the FE's handbook, Table 2B (Note 2):
"Expired rating: If rating expired by more than 5 years then training at CFI's discretion required plus full IMC Rating test. Logbook and Form FCL 99 sent to FCLD."
There is nothing about having to sit the written exam again - if anyone tells you there is, quote the above and ask them to quote their reference to you. If your Rating has expired between 25 months and 5 years, I guess you just have to do the test and you can be signed up as soon as you've passed.
[ 04 November 2001: Message edited by: BEagle ]