Washer won't stop spinning at the end of rinse cycle.

My Whirlpool Thin Twin washer (model number YLTE5243DQ1) works fine until it gets to the spin cycle at the end of the rinse (not the final spin) it spins up fine, but won't stop, it just sits spinning endlessly until you manually advance the timer to the next part of the cycle. The timer works fine for all other cycles and positions.

I checked the drain hose for clogs, it was full of water but I couldn't see an obvious blockage. The unit is in a small tight closet so I'm pulling it out tonight to get a better look at everything. Is it normal for the drain hose to have about a liter of residual water left in it after the drain cycle?

I'm really hoping this isn't a timer issue since the other positions in the timer seem to work fine.

Thanks!

Oh I should have clarified that it does stop spinning when the door is opened, but it will start up again once the door is closed. It's just the timer that won't advance when that particular spin cycle is running. It advances for all other parts of the cycle just fine.