Vandercook No. 4 Cylinder Trip Rack

Periodically the cylinder trip rack on our No. 4 drops down just before the cylinder gets to the end of the bed.   Normally, when the press is in print mode the cylinder trip rack raises as the cylinder leaves the feed table.  At the end of the bed and ready to return to the feed table the cylinder trip rack lowers as the cylinder goes into trip mode.  On occasion the rack drops down about an inch before the cylinder getting to the end of the bed.  I noticed that if I roll the cylinder more slowly the rack performs normally.  When I roll it a little faster, the rack is more likely to drop prematurely.   Is this a sign the spring on the Front Trip Wedge is weakening?