Xerox Phaser 7500 printing on thick (350g) gloss paper

Hi,

I own Xerox 7500 and I'd like to print some stuff on 350g gloss paper. Oficially it supports 280gsm card and 250gsm gloss papers.
I've managed to optimise settings (added maximum of +5*C on fuzzer and changed printing mode to "Extra Thick Card Stock") but it seems that's not enough to print 350g - it looks like fuzzer temperature is too low for it.

Any ideas? Slower printing will help?

Thanks in advance!