2078 chassis repairs
The problem:
The cast aluminum chassis is bent in the vicinity of the armboard. The chassis does not lay flat over the plinth surface as it should. This indicates mistreatment in its previous life. In this photo it is seen that the bottom surface of the chassis, beneath the armboard area, lifts off the plinth surface by a dimension greater than 1/16th inch.
Side view of the cast chassis shows the area that is bent.
Front view of the cast chassis indicates that the chassis is flat except in the
area of the armboard.
This shot shows a straight edge (machinists rule) laying flat over the jig
surface. This is to indicate that the jig surface is flat.
Why all the concern? The chief concern is that the axis of the tonearm mount needs to be be closely parallel to the axis of the platter.
After a straightening session:
front view
side view
detail close-up in the corrected area.
With this correction we can continue the restoration process with confidence.