I bought a second hand two stroke Mantis last year on e-bay. (I had to watch and wait as people seem to bid silly prices, but eventually got one for about £150.) It's an excellent and powerful little machine and great for breaking up the soil. Like any cultivator avoid using it on heavily weed-infested ground as you will just chop up the roots of couch grass and bindweed and make the problem ten times worse. I avoid over use as I reckon that it can break the soil down too much. (I have watched a fellow allotment holder use his repeatedly and his soil is like dust.) Mantis reckon that if you reverse the tines you can use it for weeding but I have never had any success with this.

Mantis do sell factory reconditioned machines from their Stockport base at a discount to the price of a brand new machine.

Just re-read your post bluemoon!! Yes - it fits easily in the back of my car with one of the back seats folded down without folding the handles. The tines are not ten inches - more like 2-3 inches - but you pull the Mantis backwards (towards you) and the tines dig down in to the ground. If you go over the same piece of ground several times you can easily get down to a depth of around 10 inches. Cleaning the tines is fairly quick and easy - remove the securing pin, slide the tine off, scrape clean, and re-secure. (Keep spare pins in your shed!!!)

The Mantis has certainly helped me.

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Gardening is a matter of your enthusiasm holding up until your back gets used to it.