I found that if you can get the part that is all push in and wrinkly into hot water is better than the steam trick,or even putting the part under a hot running tap.
At the end of the day though all the tricks work even the steam one.
If you really like a F4F wildcat then you might want to have a look at this bad boy,it's smaller than the PZ one but it's a hell of a lot faster and cheaper.
Some people say it's not as scale looking as the PZ warbirds but for the size and the good price i was more than happy with my one,i even got another one in the fun fighter range which is the RareBear and boy does that one really move along in the sky too,a bit faster than the F4F IMO.
May not be for a beginner but might be worth a look for the future and for the people out there who likes a fast little warbird,and they are fast.
I do hope you got your PZ F4F sorted out though and will have a few more good hours out of her yet,so happy flying and stay safe.