Clunks are bad! It typically indicates something is loose and it is heavy and reacts to sudden velocity changes from a stepper motor.

Typically these can be found by putting a finger in a safe place near the suspected member of the system that would provide positive feedback.

There is also something quiet common but not often associated with a mechanical "clunk". That is filament stripping by the filament driver gear. If the velocity of the filament feed is greater than the nozzle can melt and output, then the next weakest link will give. In this case, that is the filament driver gear. If it cannot drive filament forward, it will simply strip the filament and skip that particular advancement. Excessive stripping will fail to forward the filament for the remainder of the print. This excessive case is easily noted by studying the filament and looking for a scalloped section of the filament where the driver is just free-wheeling.

In my case, the stripping of filament has a very distinct sound. Hopefully that is all your are dealing with. That simply means you need more temperature or reduced filament velocity.