After my hand hand throttle issue I had this weekend I got under the SEE to take a look. The bell crank that is attached to the accelerator pedal from the hand throttle (#23 on the parts drawing 0040 00-2, P/N 406 300 09 04) is bent. What should be a flat plate perpendicular to the shaft centerline is curled like a potato chip with both arms bent inward, thus the relationship's of various components is off which probably reduces the stroke on the roads going to the injector pump. One arm connects up with the hand throttle linkage (#28 and the other and has the roller (#21) that rolls on the remote control lever (#15). The roller is no longer aligned with the remote control lever face and the hand throttle arm is bent enough that I expect the threaded rod end popped off the ball stud. I could reach up and bend the bell crank to get the roller to track better but I expect that its not a permanent fix.
This is probably a primary cause of losing RPMs that required the throttle linkage adjustment. Of course Migginsbros had replied that this part had a torn weld on his truck so that's a possibility that's its not bent rather a weld is cracked.
I have decided to order a new bell crank from Scott at EI as well as a new threaded rod end and a throttle bushing. Interestingly the parts breakdown does not show the retainer clip that was used on the threaded rod end at the fuel injection pump even though the part number is same for each one (991 24 22). Luckily I bought spare clips in case I can use one on this end and have a new threaded rod end on order. I expect I will be revisiting the injector linkage adjustment to put it back to where it was. It looks like if I remove the alternator access cover and the alternator I can get my hands in there to work on this linkage. I can see it from underneath but its a long stretch to get to everything. I expect someone with a lift might be able to get at it from underneath easier.
A general note, over the couple of years I have had the SEE and reading various forums it looks like these components were under engineered out of the factory. The first SEE I looked at had a screwed up throttle linkage and given the number of reports out there its looks like this was not a one time issue. I also see various sellers selling parts for the hand control assembly so that's another indication. Possibly a good spot for some entrepreneur to come up with a heavy duty version. On my 1300L there is no manual control lever, rather its a knob on the transmission plate that screws in and out to adjust RPM. In order to shut off the engine, I have to push down on the knob or lift up on the accelerator pedal.