Mortgage this summer

[Threeof5]

I figured this was the best place as any for my first post.

I'd like to apply for a mortgage this summer, likely in June. I had a personal catastrophe about nine years ago in which my credit went to snot. I've since recovered a bit but have some work to do. I have three credit cards and one store card. 

Chase Slate: $500

Cap1 QS: $1000

CU MC:$2500

Store: $1050

I have a previous paid off mortgage but it was over ten years ago. I paid of my car loan in April 2015. I know having an installment tradeline is important (funny enough, I'm a mortgage loan officer myself). I don't need a new car though. I'll be debt free in March. 

My questions are: should I apply for more credit cards in the meantime? Should I ask for CLIs (though I opened Chase Slate in November)? Should I take out a PLOC just to have an installment tradeline? 

I do have a judgment from a Best Buy account that went bad; I paid it over three years ago. It recently fell off my Experian report, yet it's my lowest score. I thought that score would shoot sky high after my judgment dropped off. Fellow loan officers I work with can't explain it either.

Edits: Grammar