It is more a case of the earlier the machine, the better the quality.  In an effort to reduce costs, the factory in Germany introduced more and more plastic parts, many of which are no doubt becoming brittle after 40-plus years.  The last SG3s out of the German factory has the lattice-work die-cast frame side plates replaced with steel stampings.  Probably adequately strong but it meant that you couldn't get a long-handled typewriter brush in through the sides to clean inside.  The factory had conveniently forgotten about that !  When production went to Mexico in the late 1970's, the latticework sides were re-introduced.  Quiet cheers from typewriter engineers all round !  Of course, the Mexican machines continued with the plastic parts that the German factory had fitted.  At this time, production of the SG3L (Luxe) finished, which meant that you could no longer buy an SG3 with a paper injector or double print spacing.  All you could get was the SG3N (Norm).  So basically yes, German machines can be better, but only the older ones.  The very first SG3s from the early 1960's were similar in build quality to the famous SG1 - but being that old, would possibly be quite worn by now.  The Mexican machines were still streets ahead of other manufacturers offerings in the same period though.

Thank you both. And thetypewriterman, thank you for the history lesson.