GR translation: over the metal frame / at that exact angle

[Mike Jing]

V517.36-41, P526.28-24   —and, too, with only the grim sixth sense, as much
faith as clear reception, that the B of Many Subscripts just over the
electric horizon was really growing closer, perhaps this time as “Biw ,”
the precession angle of the gyro, moving invisibly but felt, terrifically
arousing, over the metal frame toward angle Aiw (which is how they have set
you the contacts: to close, you must see, at that exact angle).

Does the phrase "over the metal frame" modify "moving", or does it modify
"felt"?

The phrase "at that exact angle" follows "to close", and "you must see" is
parenthetical, is that correct?