SR150 - - Received signal peaks with Preselector AND(?) Final Tune control

[W5SU]

I happened to look at a YouTube of an SR150 and noted that adjustment of the preselector AND final tune control produced a peak in received signal.   

(Look at 2 min's 22 Sec's, 4 min's 53 sec's, and 6 min's into the following:  http://www.youtube.com/watch?v=oYCF34r5vsg)

My SR-150's received signal, as expected, peaks with adjustment of the preselector knob.   But the "final tune" control has no effect on received signal, only transmitter output.  It seems to behave OK in other respects.

Is there something peculiar about the SR150 on YouTube or does mine have a problem?  Is there more than one design of the SR150?

'73 and Thanks

Carl - W5SU
Dallas TX

[KB4QAA]

http://bama.edebris.com/download/hallicra/sr150/sr150-sch.djvu

The way I read the schematic the Final Tune capacitor C122 (lower left side first panel) is not even in the Receive line.  There is a TX/RX relay at the antenna that switches the lines.  Note the schematic is damaged and the traces are difficult to see.

I can't account for how the video performs. 

[KB2CPW]

None of the hallies I owned or own do that. The preselector only will peak rx and tx, none of the final controls will affect the rx.