Weird thing is that lately a member here bought a new Rosedale tenor and that was loaded with issues too .. that yours didn`t work says more about the "Well known tech" than G4M
The Return G4M Straight sop I got for the missus didn`t have much wrong and most of that was regulation as the adjustment screws aren`t held in with Loctite and were loose, it`s miles off from being a Yamaha 475-II or a Yani 901 but nonetheless was a very good sounding and very playable horn, fantastic value....... Still plays fine now , Ask Vlad , and that`s after being setup by a wedding photographer ! .
The issue with G4M, with anything is that they`re merely box shifters, the customer is the QC but the price reflects that, it`s how they can sell stuff cheap - you can pay far far more for generic Chinese horns , if you want QC and a more reknown name stamped on the bell such as Conn-Selmer USA, Buffet or TJ