GE Front Loading Washer Won't Drain or Spin

My GE front-loader washer advances through the cycles, but will not drain or spin at the end. During the spin cycle, I sometimes see it agitating as it does during the wash cycle.

I have read other threads here about similar problem with the Frigidaire version of this washer.

Recommended solution was check/replace door lock - see http://forum.appliancepartspros.com/washer-repair/513059-frigidare-washer-front-loader-fills-water-no-spin.html

Recommended solution was check/replace motor/speed control unit - see http://forum.appliancepartspros.com/washer-repair/514512-washer-wont-spin.html

Recommended solution was check/replace pump - see http://forum.appliancepartspros.com/washer-repair/498053-frigidaire-front-loader-wont-spin.html

Any help appreciated - thanks.

Problem fixed - see solution below.

Apparently the washer will not enter the spin cycle unless/until the water has drained from the drum.

I removed the lower panel to check the drain line and the pump. The drain line was clear, but the pump was clogged with a fabric softener dryer sheet (I could feel it when sticking my finger up inside the pump). After dislodging and removing the dryer sheet, everything seems to function normally now. Wahoo!