Tuning Leshiy huma reg orings

I've since bought 2 huma reg for my leshiy because when i purchased an oring rebuild kit from brian and huma air none of the replacement orings will allow my huma reg to fit the reservoir tube. The O rings fit the reg just fine but its just slightly to thick that trying to slide the regulator in the tube is impossible. I don't want to purchase another regulator. Any suggestions?
 
https://youtu.be/9CeTrjybfYI

If this still doesn't help you... Not stated in video but...

You can just unscrew the manometer to vent it while trying to push it in/thread the Leshiy tube back in to relieve the trapped (degassed) air pressure preventing you from shoving it in.

If its the plenum not going in then you should have cracked the small degass screw already and don't tighten it back up until the job is already done.