I've had it with rhubarb

I swear by Timperley Early. Dig a large hole and fill with compost/soil mixture and each year when it's died down cover with manure and, in spring, thrown on some blood fish and bone. I have had excellent result in a moist clay soil in partial shade and on an exposed, loamy site. I never run out of the stuff. I've split it twice now.

I have had excellent result in a moist clay soil in partial shade..

And there in lies the problem I think. It just isn't going to grow well in my sandpit.

Is it in a dry position, that makes it more likely?

It's overshadowed by next doors trees but I wouldn't say it was dry at the moment, it had a good spent compost and chicken poo mulch in the autumn.

It was on it's last written warning this year, after 9 seasons of failures I think it's time to give in. 

I never find it running to seed to be a problem. I just snap off the flower spikes and the rest of it grows as good as ever.