LINN PCB 018 (Speed-Checker, 300 Hz Turntable Strobe) Questions to the Circuit Diagr.

Follow questions rises up to Linn's speedchecker when looking at the circuit diagram (schematic under the first attached image):

1) What is the reason for the not present of Rx, which determine the idle current through the first transistor of the darlington LED driver ?

2) Which task has the connection at the other end of R2 (here is a not connected solder pin provided) ?

3) Why a jumper at R1 to the popsitive rail (Vdd) ?

4) From where I can get the genuine enclosure (no longer available from Linn since any years) ?

Best thanks for advices in advance.
 

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