They had the EM game and were transitioning over to SS. So they'd take existing EMs and modify them to be run on the SS platform. Some they already had a bunch of EMs and made a few SS versions like Bow and Arrow. Other times it seemed like they really wanted to make the SS version but probably made a few EMs just to compare like Evel Knievel.

Operators didn’t know how to maintain and service SS so could kill demand. Also not clear if players would be ok with the play experience changing to more digital (sound, score reels, etc)

Huge transition for an industry to make. It was before my time, but had to be a scary one (alas, justifiably for folks like Gottleib)

That's pretty much the answer. I was in the business back then and saw the whole thing.
.................David Marston

That was a whole new technology. Boards will eliminate service problems. ( HaHa ).

Operators were slow to adapt to new technology, especially since this was as video games ( low maintenance ) were gaining traction on the industry.

Once operators saw what the solid state pins were earning compared to the EMs, they wanted the new solid state pins.

LTG : )

I think some national markets were more conservative and stuck with EMs longer. It’s very rare to see the EM version of Gottlieb‘s first solid state games in classified ads here in Germany, but go to Leboncoin.fr and type in Gottlieb, and there will usually be at least one EM Cleopatra or an Eye of the Tiger for sale.