M.T.H. PREMIER U50C Operating Instructions Manual page 15

To replace the lights mounted to the inside of the shell, remove the shell, and
slide the spring contact bracket off of its post. Remove the light bulb and
wires taking care to notice the path that the wires take on the inside of the
shell. Replace the bulb and reassemble the engine.
Spring Contact Bracket
Figure 10. Replacing the Lights Mounted on the inside of the Shell
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Premier U50C Diesel Engine Operating Instructions