I have recently purchased a Mercury 8hp to use as a kicker on a boat I am restoring. When I took the motor out for a test it went from shifting a little hard to now being unable to shift it out of forward gear. This motor has the shift control integrated with the throttle control via the tiller handle. I could find two service manuals online, but neither covered this SN. I have ordered what I believe to be the correct service manual, but it will not get here for two to three weeks. Any ideas what the problem might be? I am mechanically inclined and would be comfortable servicing this if I knew the order of disassembly and assembly. All help appreciated!