I have seen a lot of Johnsons and I myself have one that has worked flawlessly for over 30 yrs.
Of course I make sure to keep the vessel it is in in tip top shape.
Oh btw you have to make sure you use a Johnson frequently unlike other pieces of equipment if it sits around too long without use, things get all mucked up. I recommend bi weekly runs on the vessel of choice even if it is only for a short trip. Noon seems to be a good weekday time as other distractions are usually clear of the ramp at that time. On these short trips it is important to run the Johnson until it heats up and the temp valve opens allowing the ejection port to spew. That is the only way to ensure proper functioning.
No but shaft length does affect performance and the power head size does seem to affect the power.
I told her it still got us from point a to point b but she said yeah it just took a bit longer
In that situation you just have to mount your Johnson low on the transom and make sure it is tightly applied. Or so I have been told.