Nice bike! The Sugino crankset and SunTour derailleur set are world class, and the geometry looks pretty good, as does the color.
Remove the chainrings and watch for visible wobble in the arms of the spider when you spin the cranks. You can also mark the maximum lateral and medial excursions on the chainrings, then remove and replace them with a 2-bolt / 144-degree offset. If the maximum excursions are in the original positions relative to the chainrings, just replace the rings. If the excursions are in the original positions relative to the cranks, remove the right crank and reinstall it advanced by 90 degrees. If this alters the positions of the maximum runout points, you have a bent spindle; otherwise, you have a bent spider or, most likely, eroded spindle opening in the right crank, which then needs to be replaced.
Also, make sure the right crank is properly seated on the spindle, with the bolt torqued to spec. and that the bottom bracket bearings have very little, if any, play.
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069