I did have a couple of loose solder joints on my Wessex Champion within the first year of use. I think this is pretty much a "feature" of a lot of Chinese manufacturing and "quality control." I also had an issue with the threading of a valve/valve-cap. Again, I see these as broad Chinese fabrication and Chinese quality control issues. I fixed all the issues myself (resoldering joints, etc.). I've seen comparable quality issues (such as quality of brass and valve/cap threading on other non-Wessex Chinese horns I have. Recently, I've bought some mid-level (in terms of quality/cost) Chinese optics, and the quality there seems to be very good. There's an evolutionary process going on here -- similar, I think, to that of Japanese quality after WWII.
I have been told -- by a very well known and competent tuba tech and rebuilder -- that such issues are not confined to Chinese instruments but are a consequence of machine-soldering techniques being broadly used today in brass instrument construction. For "unusual" instruments (i.e., relatively low sales volume), I wouldn't be surprised if the incidence of such problems is higher.
Gary Merrill
Wessex EEb Bass tuba (DW 3XL or 2XL)
Mack Brass Compensating Euph (DE N106, Euph J, J9 euph)
Amati Oval Euph (DE 104, Euph J, J6 euph)
1924 Buescher 3-valve Eb tuba (with std US receiver), Kelly 25
Schiller American Heritage 7B clone bass trombone (DE LB K/K10/112/14 Lexan, Brass Ark MV50R)
1947 Olds "Standard" trombone (Olds #3)