shipwright you asked
A couple of weeks ago I bought what seemed to be a 1956 (from the serial #) Greenie. While investigating a slipping Gilmer drive I found a few anomalies.
1) Only two screws on the belt cover
2) The Gilmer drive hub has the set screw but it is on the end sleeve, not in the splined part of the hub. (Yes, tightening it fixed the slipping).
3) The eccentric tensioner is secured by the screw and washer, not by the earlier clips.
4) There is an inspection hole behind the logo cover.
I don’t believe any of these should be on a 1956 Machine? Am I right?
To make things interesting the belt cover is green, the main body of the headstock is grey, and the motor pan is gold.
What is the serial number? That could help but the serial number is on the vent plate attached to the belt cover. If it is not the original Belt Cover for that Mark 5 it may not be the original Vent Plate and serial number either. There is a lot of missing information for 1956 and 1957 as to beginning serial number for each month's production.
1) in 1957 the Belt Cover changed from 6 to 2 screws to attach to the Headstock & Motor Pan. The Headstock & Motor pan changed accordingly.
2) From what you say this is a clutched Gilmer Drive not the earlier non-clutched Gilmer Drive. The change from the original non-clutched Gilmer Drive to the clutched Gilmer Drive occurred by July of 1954. The beginning picture (shown below) from Jacob Anderson's video shows a non-clutched Gilmer Drive on the left and several clutched Gilmer Drives in various stages of disassembly to assembled. In 1956 the nylon cap was added to the drive sleeve to reduce noise.
3) In June 1955, beginning with serial number 298476 the Eccentric Bushing included a set screw. Mark 5’s before this used “rocker shaped” bearing retainers. These "rocker shaped" bearing retainers were not on the earliest Mark 5's produced.
4) October 1955 was the change to B Headstock at S/N 312508 included a hole behind the rear Name Plate. At that change they still used 6 screws to hold the Belt Cover on the Headstock casting and Motor Pan.
Parts get changed over time. It is possible that the Headstock looks "off" due to damaged parts being replaced over the years. The same may be the reason for the different colors. By "1) Only two screws on the belt cover" it would be a 1957 or later but all other questions fit a 1956 Mark 5.
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