I have a used Trombone<EMOJI seq="1f451" tseq="1f451">👑</EMOJI> KING Cleveland 605 with a single trigger But it doesn't produce any sound just buzzes and when I press the Trigger it then produces a very good sound tone. The serial number for the Trombone is 776395 and there's a small number "196" inside the rotor engine of the trigger... thanks to anyone suggestions please

The rotor might need to be re-aligned. Take the cap off the rotor and look for a mark on the rotor and two on the rotor case. They should be aligned when the rotor is open and closes.