If the receiver is a little larger in dis then you are when hard it should be alright. The liner MIGHT be to small, as it’s fairly cheap I keep several different sizes around to experiment with.
I start out totally soft on lowest speed and draw max air out, thus enjoying being sucked in and squeezed tight. As I firm up I add air in a little at a time and increase speed a bit thus getting some stroking going. The more air you put in the longer the stroke should be. Once hard vary the speed for different sensation. Too much lub is hard to do, if you side all the way out from over lub take more air out should help, if WAY over libbed you may need to hold it in place for a bit. During long sessions I add lub by dripping it right at the base while the receiver is up some, slow speed works best for this. As it sucks the lub in the stroke increases. Max stroke seems to be about 4.5 inches for me so I “walk” the receiver up and down my shaft to work different parts.
The speed and the air are yours to play with, uses them a lot, the controls don’t seem to wear out and they make the venus do different tricks on you. Shortage of lub will restrict stroke. Learn to enjoy, experiment to find new thrills.