We only sell the manual to current owners of our products. This is to give our IP some protection from people attempting to copy our products (though it would be quite difficult to copy without our proprietary transformers). When you acquire a used Mainline be sure to ask the current owner for a copy of the manual. If the current owner does not have it they can purchase a replacement from us after we verify their original purchase and pass it along to you.
I should share here that we have had some email communication and your story seems to have changed from those emails, where you requested a manual for your technician to examine to determine if he wanted to build the kit for you. I explained at that time that the manual would be provided immediately for download upon your purchase of the kit.