Yes they do advocate that one of the ways is the oven. Before you do that read the instructions carefully that you do not exceed the stated temperature and the times of heating. I will take a look sometime today when in the studio about the instructions and let you know later.
For acrylics I just use a standard hairfryer (Oops, spelling mistake
) hairdryer. The heat gun is too drastic a measure.
If you are not happy changing the original then try another similar one and then compare the two. Maybe sometime post the 2 together so others can also see the result.