This machine was made by Gottlieb in 1979.  They are not rare with a production number of 6150 but are harder to find then some other Gottlieb system 1 games such as Sinbad which had 12,000+ production.  Keep your eye on eBay they come up a few times a year.

This game uses the Gottlieb System 1 processor (CPU).  This is renown for failure and is difficult to repair, as it has custom "spider" chips on the board. They were called spider chips as they were double legged and look somewhat like a spider.  If a spider chip fails new replacement chips are not available.  However new CPU boards manufactured by Pascal or NiWumph are available if this should happen.  If the board is working and the battery removed and correct fuses in place there is no reason the cpu wont continue to be relaible.

Hope this helps. 

PS here is the link to this machine on the Internet Pinball Database http://www.ipdb.org/search.pl?any=Hulk&search=Search+Database&searchtype=quick