flight deck st 4400 shifter replacement flight deck st 4400 shifter not working. I have sprayed it and a man said is was US. What other shifters can I use new or used. I do not need the electrics cheers Steve
It's my understanding that all Shimano shifters below 11 speed ([except ST-4700][1]) use the same cable pull ratio. This means you can use any Shimano 9 speed rear brake/shifter unit.

Tiagra ST-4400 obviously and ST-4500, and Sora ST-3400 and ST-3500. 

The newer Sora may be as good as the older Tiagra. Some googling and looking on Ebay may yield a replacement matching ST-4400. Or you maight choose to upgrade both brake/shifter units.