Do u still have the rubber plug that goes over the flywheel inspection hole? Mud gettin into ur bellhousing and fillin ur clutch would prob do exactly what ur sayin. Would take a little while for it to clear all the crap and allow the clutch to engage. Best idea would be to drop the box and clean it out (check ur clutch surfaces while ur at it - mud + clutches =
). Make sure it's well sealed when u reassemble (hell i'd even use some silicone to hold the rubber bung in so ya don't lose it lol).
Edit: if i'm reading what ur sayin right....
