most of these small gas engines (string trimmer, tiller, chainsaw) use an Inertia type "clutch" These "engage" when the engine is fully rev'd up. In many cases stale or older gas does not burn as well so the engine does not come up to full speed.
In tillers debris or weeds can often Clog the tines these need to be keep free of "tangles"
I actually had to rebuild a small Mantis tiller several years ago. One of the men that was an original co-founder of our company had a Mantis tiller that did just what you described. I believe I remember ordering a clutch and had it put back together in about 20 minutes. I remember that it would run and spin the tines, but as soon as you touched ground with it, the tines would no longer turn.
If you are not handy with tools, you will need to either find a friend or take it to a local shop. I don't remember the price of the part, but the labor was not too bad to fix it.
Thank you for the time and tips u shared
You can always go old school on it ( the garden) and pick up your trusty shovel and hoe.
thank you for your tips every one have a great day!
i carried my Mantis tiller to the shop 6 blocks away to get it serviced this fine misty am! Thank you to everyone for giving free advice and tips and great ideas