These are tough ones. I have fought the same ones and have made the same changes as you have. That said here are a couple that were successful for me that you can try. On one job I moved the Power to the Car top Encoder from the Zap Board to the MR Controller, as if it was a Governor Encoder. That eliminated the the 45 for that car. On another job, changing the Acel Decl time in the Drive took care of the 45 error. The car would occasionally overshoot the floor and throw a 45. If you have changed The acel/decel in the MSU you should look here 1st. also a flaky contact on the M Switch can throw a 45. Just a few more to try. Good Luck. AS a note all the 45's I encountered were on MODS