No corrections here either !! But I would add to check the rocker covers themselves. It is common for an old shovel to wear the bores of the rocker cover where the rocker shaft is supported and sealed. The Rocker covers are only aluminum and they are what holds the rocker shaft in the correct location. The bores on the Cone side of the motor tend to elongate and this can cause unwanted up and down movement of the rocker shafts. Remember we are talking thousandths of an inch so don't always expect to be able to see it. If you have had any leaking from the rocker covers at the rocker shafts, I would pay close attention to this area.