From the outside the platter shell appears undamaged, although it is warped and in need of minor straightening to eliminate clutch rubs. But that is not the purpose of these photos. Rather I have found yet another small detail difference between early and later TD124 players.
I was beginning to disassemble the platter mat from the aluminum shell by removing the three machine screw fasteners within the 45 hub adaptor when I noticed that the machine screws seemed unusually tight and unwilling to be removed, so I took a look from underneath and found the following:
This 
instead of ------- this: 
Now a side by side:
The detail view that is labeled "Should Be" indicates the presence of a backing plate with threaded holes to receive the machine screw fasteners. This version is common to most outer platters. The detail view that is labeled "IS" indicates the absence of this backing plate. Originally, I used the terms "should be and is" because I had not seen an outer shell assembly like the one on 2078. However, upon close examination, The "is" platter appears to have been deliberately manufactured (by Thorens) in this manner.
What I conclude is that #2078 is indeed a very early production model. Btw, this platter shell and the other slightly different platter shell assemblies are interchangeable between TD124 players. No dimensional differences in terms of form, fit and function.
As I see more and more examples of the TD124, I find several minor detail differences between them. On #2078, the outer shell does not use a backing plate to secure the 45 adapter to the shell, instead three threaded holes exist within the body of the shell for the 45 adapter to fasten against.
Btw, the 45 adapter was successfully removed by putting some WD-40 (a penetrating lubrication) over the threaded fasteners and allowing the lube to penetrate into the threaded holes overnight. The next day, the three machine screws easily turned out, allowing the 45 adapter to be removed with no harm to the shell, fasteners or 45 adaptor.
