The rubber hose that feeds the wheel cylinder has failed. It is restricted internally.
Check the wheel cylinders - they may be leaking and you can't see it on the outside of the wheel
There is no fixing it, it must be replaced.
You need to "bleed" the brakes at each wheel. R
They are not adjustable, if loose they must be replaced.
Wheel cylinder stops would keep the wheel cylinder from coming apart.
Did you bleed the air out of the hydraulic system after changing the wheel cylinder? If not, you must do so.
The wheel cylinder has failed and will need replaced.
if slave cylander is bad, it must be replaced to fix it
If the rear wheel brakes are locking up on a vehicle they should be thoroughly checked. The master cylinder may need to be replaced on the car.
A common cause of problems in cylinder head gaskets is leaks in the gasket. When a leak forms, the gasket must be replaced.
When the cylinder was replaced, did you get new keys for it also? Using a worn key has this type of symptom regardless of the cylinder.