It is probably too low current being supplied from the stepper driver, you can probably tweak it a bit. It may also be your temperature too low either because you are setting it too low or maybe the temperature feedback circuit is reading high. First step is to turn up your print temperature and see how that goes.

Spring loaded extruder isn't really an improvement or an upgrade, it is just different for different uses. Do not lose your old bits, you may need them.