The most reasonably priced component used on the T20 Tc250 Scrambler 1969 Usa (e03) Oil Hose - Oil Pump-tachometer Worm Gear is the O Ring(d:1.3,id:7.6).
A sample from the products for the Oil Hose - Oil Pump-tachometer Worm Gear include: Gasket(6.2x11x1).2 (nas), Oil Pump Lever Pin, Washer,lock, Oil Pump Lever Chain Connector (tc250tc250).
In this schematic the "Washer,lock" is used most often.