No probs Adam, I am fully experienced in windows - done 3 for myself.
I will gladly do them for you. Its a HF welder not RF!!!! High Frequency, like a microwave between two narrow plates. The same as they use at Ringwood Flexigoods.
I could possibly run over your seams if required! (feel the confidence, anyone would think I had spent more than a couple of hours infront of it, though I had a good teacher!!!!)
Rob