A Mityvac is the right tool to use to check diff locks, even with the vac reservoirs. Yes, replace the hoses, test the check valve in the engine compartment as Phil suggests, and make sure they are connected properly. -- Dan Simoes dans@ans.net ANS Communications http://coimbra.ans.net/dans.html 100 Manhattanville Road (914) 701-5378 (voice) Purchase, NY 10577 (914) 701-5310 (fax)