Kathryn and I tackled the replacement of the water heater elements.  We I got the water heater my brother had set me up with all the required items: replacement elements, user manual and wrench socket. We went the safe route and rather than try to “change on the fly” we completely drained the tank. It was tricky replacing the lower element as the element was heavy to get lined up correctly and finger thread.  The 1^st time we had a small leak and had to re-drain the tub and re-seat the lower element. We finally used a vise grips to get the lower element aligned and inserted. Our water has had sediment issues – this year especially.  I suspect that was a major contributor to the demise of the original elements.  But we have probably had the water heater for nearly 30 years; hopefully we can get another 30 year run !