My Spring Airs in both airplanes will bang down with some authority but when upright the nose wheel will frequently not lock when operated inverted.

Any air up/spring down system must operate rapidly to function any attempts to slow the extension down will result in failure to lock especially the nose wheel

Do check that your system when retracted is fully in the up position if it is not then the spring will not be at full advantage during attemps to extend agine resulting in locking failure

.John