Refreshing/renovating an old compost heap (or three)

I currently have three plastic cube-type composters, which have been neglected for a good couple of years.

The lids have certainly fatigued, and are in bits, and from what i can see on the top and at the "hatch" area at the bottom, not much composting seems to have gone on.

The ingredients were mainly a mix of grass clippings and aubiose/chicken manure.

I'm really keen to get composting again, and I might even try to do it "properly."

Any ideas on what to do with the current bins?  should I just  empty them, bagging up any usable compost and restarting the rest?  I have plenty of nettles I can bruise to add as my "green" component at the moment.

should I just  empty them, bagging up any usable compost and restarting the rest?  I have plenty of nettles I can bruise to add as my "green" component at the moment.

That seems like a good plan, and if it's all very dry then dampen it down a bit as well 

snap jay