I've never had to push more than a little on the bolt, usually with a straight shot... but, lets see...
What was causing my bolt stick was my trigger went out of time. The adjustable rod on the sear had moved. You want to pull the trigger forward (opposite of firing), as far as you can, and adjust the rod so that it does not touch the trigger when the marker is aired up, cocked, and the trigger is pulled forward. You want 1/8"-1/16" gap between that rod and the trigger.
If you have a powertube spacer (newer), check to see if it's damaged. Replace if need be. If you have a powertube spring (older- replaced with spacer), replace it with a powertube spacer kit (you'll have to try several sizes)
Those are the only solutions I know for it off the top of my head...
edit: the Powertube spacer or spring is underneat the powertube tip, the brass piece removed with a coin. Remove it, there should be an O ring or two, then either a brass tube or a small spring
Got an Outlaw game in the LA or San Francisco area? Please PM me!