Summary: Trying to save money, replacement check valves are $15, is that likely to fix this issue?

Pictures of the cartridge: https://imgur.com/a/eAZ2mgu

My bathtub faucet goes off > cold > hot. Recently when turning on my hot water, I hear/feel a thump coming from the cartridge, and the pressure drops off. In the video I tried showing it but I’m unsure if you can hear the thump. There was one tiny (like 1/4 grain of rice) piece of sediment in the check valve, but everything seems clean and I flushed out the lines for 30 seconds before reinstalling. I can barely shake the cartridge and the metal slide balancer slides freely.  The check valves get stuck open when I push them down with a pin, like the spring isn’t stiff enough to push it back closed. Could this cause my pressure issue causing the balancer to lower my hot water pressure? Any help is appreciated. I would love to remedy this with a $10 check valve than $70 cartridge replacement. I believe the cartridge is Peerless brand. 

Thump then low hot water pressure at bathtub faucet. Could it be the pressure balancer in the cartridge? Weak check valves on cartridge?