Hello from NH. I am at work and I just read your inquiry. Off the top of my head I believe I do have an extra manual for my GL1800. When I get home at around 3pm I will check for sure and then I will post back. Hold on I am 99.9% sure. I will send you an email when I verify that I have it.
I found my owners manual and I thought the second one I have would be with it. It's not. The only place I can think of is I might have given it to my mechanic for when he works on it. I will check with him on that and if he has it I'll just get it back from him. Its no big deal; I will work on this.