These Hamamatsu UV-Spot Light Sources can be found on spin coat tracks such as the Dainippon Screen DNS-80, DNS-60, SK200 and others. GetSpares.com, LLC has them in stock fully tested and ready.

L6001 From DNS SK200

The part number for the whole exposure assembly is L6001/L6299.  One of the common failure modes is when the UV light will not ignite or has a weak output.  The obvious culprits are the 50Volt igniter and the lamp part number L6190 / DNS 2-39-51072.  Assuming that those are known to be good, the next common failure is with the AG09 50V power supply.  These power supplies units can easily be swapped out with 8 screws in less than 10 minutes.

8 Screws to remove power unit