The factory supplied springs are about as much use as a chocolate fireguard.
We built 2 RV12's and during the initial fly off testing 6 springs failed !
We replaced all of them with after market stainless ones and have not had problems since.
This was flagged under a maintenance MOR to Rotax and as at this time, a year later - no reply.
I would junk the factory supplied ones, replace with stainless ones from your usual supplier and squirt a stripe of RTV along the length of them to stop harmonic vibration.