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One easy check you could make is to verify if pedal spindles (axles) are straight.

IIRC you purchased these new as replacements so they should be fine.

Simply one variable to eliminate in your investigation.

Crank arms can be checked with a straightedge - any piece of material with a milled edge will suffice.

Since the arms do not match each other either one or none are original to the bicycle.

The drive side arm is the more nicely finished of the two, but this does not necessarily mean it is original to la bicicletta.

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