Edit: Nevermind, I noticed you are already using decks. Maybe somebody else will find this interesting.
I have one nifty tool for dealing with randomness, and avoid the same event happening over and over again. I noticed it in another game, and I use it in mine.
Decks!
Imagine a deck of cards. Let's say there are 4 cards. [A,A,A,C].
Let's say we draw a random card from the deck, and it determines what event happens. As we see, card A represents more likely event, having probablilty of 75%. Event C has 25%. We pull cards from the deck until there is nothing left, then we just reset it.
What advantage do decks have over a simple random value?
1. We never have long streaks of unlikely events (It's impossible to get three C's in a row, and only improbable with randomness)
2. We quarantee that the rare events happen eventually (So there are no long streaks of likely events either).
There are disadvantages to this system (if the player knows about the deck, and what cards there are, they can have a good chance of predicting next events), but it is a nice way of making sure the player is not screved by randomness.