Try immersing it in warm water and letting the drum stand for a while. This is an issue in colder cliates and one I doubt Charlie has dramas with. Failing this try VisioPro which is a BeckerUnderwood product applied at 1.2 litres per Ha although it has been used successfully at 2L per Ha. Thus has a high degree of tank compatibility so can be used in a tank mix with no dramas. And yes before anyone carries on I do supply it!
I use this product and have very much the same problem (and I am further north than Charlie) Its just the way it is, some tins come out easy and some are terrible to mix, pour the liquid off and fill the tin with warm water and stir then pour the liquid off again and keep doing that until you get it all mixed, some times I have to get my hands in the tin and mix it by hand...helps a little.