[FERNSEH]

Second thoughts about the metal sub-frame. Without it the chassis is somewhat flexible which could impose too much strain on the neck of the CRT when the chassis lifted off the bench prior to reinstallation in the cabinet.
The same rule applies when the chassis is removed from the cabinet for servicing.
The right angle at the front of the sub-frame will be cut off. See attachment.
Doing this will make the underside of the frame completely flat which will allow the chassis to be slid in and out the cabinet more easily. Countersunk screws will be used to attach the frame to the chassis.

DFWB.