A 36-pin tip for one series will not seat correctly on another series, even when the needle count looks identical on the pack. Compatibility is decided by the bay, drive collar and sealing ring — not by pin count alone.
When you browse this catalog, open the pen model page first, then choose a tip listed for that model. Shared or "universal" series appear on every pen they fit; still confirm the connector against your own instrument.
If a tip clicks on but wobbles, fails to lock, or leaves a gap at the seal, stop and swap to the correct series. Forcing a near-fit risks poor performance and can damage the drive mechanism.