Which version of Rules with which version Entity API?

Having terrible trouble attempting to install Rules on my site.
I'm sure I've made a total mess of things.

I had it there at one point and worked with it a bit but it wasn't working so I deleted it, possibly without properly uninstalling first? (bad girl). I was fooling around with Notifications as well which seems to be messing everything up as there are leftover tables from those. So now there's all sorts of junk tables in the database. i.e. rules_config, rules_dependencies, rules_tags, rules_trigger. Trigger has now been disabled but cannot uninstall it.

Now when I try to reinstall Rules I get "fatal messages" regarding missing classes
"Fatal Error: Class 'RulesUIController' not found"
"class_implements(): Class RulesEntityController does not exist

I have installed, uninstalled, rolled back, now unable to install even simply to uninstall.

Shall I drop these tables before uploading Rules?
Shall I use an older version of Rules?

I have researched many issues that seem related and have tried the Registry Rebuild (my issue here: https://drupal.org/node/2134455)

but I suspect the problem is versioning of Rules and its dependencies.

I am running PHP 5.3.26
Entity API 7.x-1.2
Entity reference 7.x-1.0

Any suggestions?

Thank you all in advance.