Too light for espresso?

This is kind of a two fold observation and question about using light roasts for espresso.

As I wrote in a previous post I picked up a bag of Costa Rica Hernan Solis roaster by Flying Goat Coffee, it's a light fruit forward coffee.

Now I have heard that there are some coffees that can roasted too light for espresso. I thought that statement was just in regards to what would taste good as a shot pulled for espresso. However, I have not been able to pull anything other than a gusher, even when bringing my grinder a few notches below anything else that I have ever pulled.

I have done a few searches throug the boards of home-barista, but yet I have yeilded no results in my pitiful attempt at trying to find an answer.

Can a roast literally be too light for espresso?

My only thinking would be there is a not enough oil brought out by the roast, which will allow the puck to conform together. However, even then I am not sure that can be the case, because at some point you think you could grind it fine enough to pull a shot.

That being said upon cleaning my Preciso I noticed something a little troubling. I do not think that this is a problem right now but it could be one in the future or most likely will be. There is a crack that is developing in the upper burr carrier. Not sure what it could be cause by. You can see from the photo it isn't going all the way through so I doubt it's affecting grind, but that was my first thought.

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So is there such thing as too light for espresso?