A site visitor has a working Model 4 (or at least drive :0 does) for sale for $300 for local pickup. Unit does have a loose connection in the plug at the power supply that powers the CRT filament, although most of the time the connection is good as is. Probably an easy fix. Drive 1 works when in Drive 0 position, so perhaps there is an issue with the controller or cable for the :1 position.
Seller is located about 100 miles NW of San Antonio, TX a few miles off of I-10; and could meet in or around Kerrville, Texas if that’s better.
If this sounds good, please reach out directly to Brick Parrish at 
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