Any light of any type used in any application is going to eventually fail, not just in pinball.

For WOZ it probably matters which type of boards are in the particular game to have an educated guess generally how long they will last.

Agreed. My point is that all lights can and will fail. The newer the version the less likely to have major problems with their functionalty.
In WOZ, original 5 volt boards had high failure rates. The 7.5 volt boards without buffer boards were an improvement. The 7.5 volt boards with buffer boards are a further improvement. Now they have version 2.0 which appear to be non-serial boards that likely will be an even further improvement.

None of this will stop certain individual lights from failing. Every manufacturer will have some light failures. It is the nature of electronics to eventually fail.

The original poster is not specific with the question so a broad answer is all that can be givien.

JJP announced on their Google Group that they have opened an online parts store. The boards are mostly available there to purchase. The question I have is are they still giving a discount if you trade-in your old board for a new one? Also, are all the little satelite LED boards the same part? I only see one option in the parts store.

http://jerseyjack.production.na1.netsuitestaging.com/Parts/Wizard-of-Oz-Parts/?range=61%2C79%2C79