I prchased a Pro Mac in the late 70's. Served me well, always needed dorctoing in some way though. ex: When the demand thumb push rod to oil the bar gave out I removed it an let the oil run freely. Had to switch to using used motor oil rather than bar and chain oil because it got pricey. I can tell you that bar an chain was exceptionaly well oiled. The new rule was, "no ideling". Cause the oil just kept comming.
Moved up to a Stihl Farm Boss - the 260 I believe. Good saw, still have it.
While tyring to take it easy on the threaded caps I went a little too easy and ended up with a leg and boot soaked with oil.
My son was the on the other end of the extreme. "Things like this only require more power". So he applied more power. Snapped the flange off the top of the cap and drove the threaded portion down inside the resivoir. He is still learning that fine point between required power to achieve the task and, "Oh ****, I just stripped out something else. Those treaded caps are not cheap.