Transmission mounts/Engine mount insert

[ftp19601960]

Internet copy of 986 workshop manual says that star nut holding transmission mount cannot be removed or whole mount is destroyed ... What is the know how (if any) of replacing just mounts with keeping original brackets?
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I noticed that stock front engine mount has slight angle of 3-5 degrees in its rubber insert mounting holes. I did not find any spec for it either.
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Front engine mount supporting bracket has oval holes. What's proper way of positioning? Simply follow originals? For suspension I simply put car on the ground before tightening to make it "neutral". Here I have no idea. Probably I need to tighten transmission mount star nut at the very end.