This type sony tubes can`t be bought new are rebuilt (new phosphore and new gun )
But they stil can be found second hand with no visible wear on the phosphore.
For a maximum light output the glycol should be checkt and replaced if needed afther this meany years of use and the surface of the tube and back of the lenses should be cleaned as well.
The electrical focus and g2 of the tubes chould also be readjust.
There are two types of tubes that are interchangeable for this type of projector the sd130 & sd187 ( 07ms probably also but not 100% sure)
I have heard that rejuvenating of projector tubes doesn`t work they are not in the same class as monitor tubes ,the phosphor will normaly be toast before a gun runs out of life.Personaly never had a projector tube with a weak gun but plenty with burn in and wear.
Bruno if you ever need tubes are help for the projectors send me a pm.   
 

 Congratulations Bruno , great achievement .
I have seen this game in 2004 when i was visiting blankenberge and the blue tube of one of the projectors was already not working.
I would refurbish the sony projectors then with same luck they can last another decade (or two).

qoute from leonk
Bottom line, eventually you will need to go to new projector as cost of bringing these beasts back to life wouldn't make sense and even if you do, you won't have the results you want. On the other hand if you do go LCOS, 3LCD or 3xDLP prepare to spend thousands for something worthwhile for this beast. But you will not regret it.

When the projectors are refurbished and have tubes with no burn in why would he not have the results he wants.
You say refurbish the sony's will be to expensive but have to prepared for spending  thousands to go digital ,goinging with the sony's wil be a lot cheaper and are optimal for the game. (think curved sreen and blend)