As a disclaimer, this is my first adventure with a non-rigid bike, so I'm a bit of a noob when it comes to suspension design.
The fork in question, despite it's negative reputation, is a 2005 Manitou Stance Flow (yeah yeah - the frame & components it came with made it worthwhile on a complete bike). Despite being a 2005, it was new when I bought it (March 2008).
The entire bike has only seen, maybe, 20-30 hours of riding. 5 of which were on trails, and not riding hard at all as I'm still getting used to it.
Anyway, here is what's going on;
It was working fine when I left my house, after an hour on the trails, and on my way back home. Hitting some bumps right near my house, the thing stiffens up and tries to rip my arms off. My 15cm of travel suddenly turned into 2cm.
I'm pretty sure it's a coil-spring only fork. No air valves to be seen & it's not fancy enough for something like TPC.
Pushing it down, it feels like it hits something solid. I noticed a slow oil leak on the right (from rider's perspective) stanchion, significantly more than the left one, so I assume that's where the problem is.
Depressing it as far as it allows, then lifting the front wheel, after a second or so, you can hear a seal break & it sucks in air. Maybe oil level problems?
Another interesting factoid - Flipping the bike over, depressing the fork by hand, it loosens up and allows for seemingly complete travel. Flipping it back right side up, this continues for a few minutes, then it stiffens up at the same point. (I'm imagining something metal slowly sliding up and down a tube? Or thick oil sloshing about?)
I found the service manual for it, which is moderately helpful. I don't have the 20mm socket to get inside the stanchion, hardware store was closed on my way home. I don't have a problem with fiddling with it or fixing it myself, but I'd rather ask first. Should I bother the crap out of Manitou to get them to fix it? 1 year warranty from date of purchase.
Cliff Notes: bicycle fork locks up, leaks oil & other fun things.