blackdog62
On the iwata if you tighten down the hose to much it puts pressure on the trigger a causes the trigger to feel stiff or spungie I have noticed it's worst after market gadgets such as water traps quick connect ext or just the hose.
I deal with it by using Teflon tape and don't tighten as fare. And there high volume an so they like higher pressure. But everybody mixes different. Hope this helps.
Something's not right with your Iwata, I guess. I have three Iwata AB's - HP B+, HP-CS and Revolution SAR - and none of them exhibit the behavior you mention. Yes, I do very firmly tighten the hose, couplings, etc..