I've got an H. I don't know if yours has the two rubber rings on its needle/tip/nozzle parts or if yours only has one on the nozzle. Mine only has one on the air nozzle, and that part never needs soaking. It's so easy to clean from the outside, I just leave that part on the airbrush pretty much all the time. Keeping the other two parts stored in thinner is ok, but no need to leave them in there for more than 24 hours. If you have the 2nd rubber ring, I'd keep it out of the thinner bath.
Once, I left the #5 tip in a jar of auto lacquer thinner for too long, and the tip of it became brittle & started chipping apart. It was weird, so the hardest lacquer stuff is good for a cleaning, but not a prolonged soaking.