The only think I can think of is that some dirt from somewhere else in the system has gotten stuck in the valve. If you didn't already, you probably should flush out the fluid in the system and replace the system filter (instructions are in the service CD).

If this doesn't solve the problem, the valve can be cleaned and rebuilt if you don't want to replace it. I believe you'll find info here if you do a search (Thomaspin may have posted some info on it).

jlc

__________________
Jeff

'87 560SEL 267K (177K on motor) Blue/Blue
'98 Buick LeSebre 60K (wife's car)
'56 Imperial Sedan 124K
Past Cars:
'67 Dodge Monaco 130K (Sold)
'87 Chrysler 5th Ave 245K and going strong (sold)
'73 Plymouth Satillite 175K (sold)
'96 Chrysler LHS 80K (totaled)