when you say it won't push out paint are you talking about spattering or just not sufficient volume... one thing on my HP-CR that was hard to relearn was how far back to pull for sufficient paint. It was a LOT farther than either my Badger 155 or 175. It took awhile to get used to that and now it puts out sufficient paint for larger coverage.
Also you might try thinning a little more than you think you have to, the BCS is siphon fed and won't be able to achieve the lower pressures for spraying that the CS and CR series do. And on that note make sure you are using sufficient pressure, try it about 15 to 20 psi and see how it works, if it works ok then go down on your pressures bit by bit till you find the lowest point you can satisfactorily spray at.
good luck to you!!!