I have this info:
Q503 2N7002, 1855-0734
Q502 BSS84P, 1855-0768
Q504 MMBF4392, 1855-0752
Q507 2N7002, 1855-0734
Q508 2N7002, 1855-0734
U502 OP-27GS, 1827-0926
The unit might have been in a test fixture or someone put it aside to take home, as a dud unit.