Hi eroosa,
I replaced mine recently from reading posts here. Some here have put dental floss through the square hole and then strung a bushing on the line to line it up and not loose it. Then snap the bushing in place and pull the floss out. When the four bushings are in then snap the levers in place.
I put a bushing on a lever then tried snaping the bushing with the lever in it into the sq hole but broke the bushing. Of course once the levers are in the bushing it expands the bushing but I tried.. Glad there were five in the box!
I then removed the unit to install the bushings. Three bolts I think and ummm, easy to drop. The holes in the unit are slotted so if you do it this way don't tighten the unit untill the levers are snapped in so things will line up. Hold the flashlight with your third hand.
I never got an engine light. I found one lever laying on the engine about a year ago before finally putting new bushings in. I just kept (mostly) the rpm under 3000 so the IMRC would not open. Got good gas milage too!
Waxhaw