the heads don't neccessarily drag. But they do bump across the surface a lot if you're using a raft. And i pretty much just printed on rafts for a few months.
I'm thinking that's probably the best explanation. The left bugger's worn.

Hmm, so use the right head till it's as worn as the left one, looks like the best quick solution. And replacing lefty in the longer term.

So does anyone know where i can get a new nozzle that the little plastic tube fits into ?