Inlet Manifold De-icing Unit 12 Volt - All Questions

Hi all, I have just purchased one of these. Obviously there is no instructions with the item. I have a 1600TP type 1 in a buggy. The item is working and getting warm but the carby is still getting really cold and has condensation around the base of it, causing the engine to loose idle and stall. Once it has been operating for a while (approx 45 minutes) it seems to work ok. I have it wrapped around the manifold just beneath the carby. It doesnt fit very well. I am guessing that the two "rings" built into the unit should line up with the vacuum port in the manifold. I am unable to get it tight enough for these to line up and didnt want to force it too much. This means the velcro doesnt line up properly and only has about half of it holding the warmer on. The manifold has the factory bend in it yet the blanket seems like it is made straight, thus not fitting correctly. Just wondering if you can help me please as it really doesnt seem to be doing the job it is supposed to be doing and is a real pain to drive in the cold weather.
Thanks and regards Jarrod