I am trying in vain to separate a 2nd Pattern foot rest from the splined (?) extension piece without success, I have not forced it as I do not want to damage it, I presume they do come apart (Naively). I have applied gentle heat and given the internal sleeve a reasonable tap which makes it move about 5mm where it stops, apparently jammed - can some offer a suggestion or give me the confidence to give it more than a gentle tap.