MSD 250 lamp issue in Technobeams

I have 4 Technobeams that are circa 1998. The Philips MDS250/2 lamps I installed in them have roughly 300 or so hours on them but the bulbs are 10 years old. I cannot seem to get the fixtures bright light they were when new. I have cleaned them checked all functions and still they just seem a little dim.
Could it be the age of the lamp vs hours?
Any advise?
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