The stakes (small nails) had been set in a narrow strip of wood (coffee stirrer type thing) and I'd even put magnetic strip on them thinking that would give them some bottom weight. The magnetic strip peeled off without too much trouble and then I took a gamble and glued them to some new magnetic strip cut to size. They were then built up with plaster, painted and flocked.
Better still, all done.
I'm also relieved to see that stakes feature in the Impetus rules. Time to make up an army list for my Burgundians so I can try them out with Impetus.