Can anyone help with a starting problem on a 1989 740GL with automatic transmission?

I recently did some rework on this vehicle, including: replacing motor mounts and the transmission mount, new brake rotors all around and new exhaust system. In completing the motor mounts I removed the usual intake stuff and took the time to clean the oil breather box and other miscellaneous items. I also disassembled and cleaned the starter wiring. Just some good preventive maintenance!

After reassembly of everything and re-charging the battery, I found that I could not turn the engine over from the ignition. I rechecked the starter wiring with no problems found. I was able to engage the starter by jumping the terminals on the solenoid. I noticed that there is an audible "click" in the relay panel when I turn the ignition to start. My manuals do not show a specific relay for the starter solenoid, so I am somewhat stumped. I pulled the neutral safety switch out and checked it out as OK. I even jumped this switch with no success in starting with the ignition key.

At this point the only way I can start and run the engine is by physically jumping the solenoid. I know that there must be some simple connection, relay, fuse or whatever that I am missing and would appreciate any help offered. I am also suspect of the ignition switch itself, but this has never been a problem on the vehicle (intermittent or otherwise), and I am reluctant to pull it out right now. Once the solenoid is jumped the engine runs fine.