Printing envelopes on HL4040CN

I just bought a HL-4040CN and all my envelopes wrinkled, regardless of the size, paper thickness or software settings (thin envelope, thick envelope, etc.). Here's how I solved the problem....Open the rear panel and you'll notice a small gray lever on each side, which is probably pointing to "A" on the scale (A, B, Envelope). Move both levers to "Envelope" and close the back panel. The troubleshooting manual says the levers should be moved back to "A" after printing the envelopes, but I left them in the Envelope position and can't see any difference when printing regular or test pages or envelopes, except the envelopes are no longer wrinkled. I called Brother and asked them if there was any reason why the levers can't stay in the Envelope position, and they told me they could be left there if it wasn't negatively affecting other documents. Now, I have a great printer that prints everything without any problems. Hope this helps.