Single Push air type (concealed cistern) requires three pushes to flush?

My cistern was frozen following a week away and upon my return I attempted to flush the loo, discovering the loo was frozen and it gave no response upon pushing the button.

When the cistern had finally defrosted the loo now requires three/four attempts at pushing the air button to build up enough pressure to flush, I beleive that I caused this attempting to flush whilst the loo was frozen, maybe causing an air gap? how do I correct this?