Ultegra 10-speed

[Roubaix08]

2008 ST-6600 shifter seems to have seized on upshift. Any ideas?

 

[si_c]

Try loosening the cable at the derailleur and see if you can move it by hand.

Could also be grime or something in the cables causing too much friction.

 

[Ajax Bay]

Douse innards, through every orifice, with copious WD40 spray or similar; and wipe; and repeat. Assume RH STI.

 

[iluvmybike]

Gear cable has broken off inside shifter and jammed it - you will need to try and get in to find the head and remove the broken strands of metal