A few years ago I was sitting in my old sky-chair when it suffered hardware failure. I fell four feet, landing on my ass on concrete. I was in pain for weeks.
After doing the above, grab a higher rung & then you can lift your feet off the ground; your weight is your weight, if it’ll support it hanging from it, it should support it if you’re standing on it. The advantage is that if that higher rung does break, your feet are only an inch or two off the ground so you’re not really going to fall
I didn’t recommend that, because there’s a non-zero chance that if the rung breaks you are going to yank it down on the top of your head with maximum force!
I was thinking something similar. The OP said something about how the ladder is almost too heavy to carry alone. So why not just replace it with an aluminum ladder? There are tripod-type ladders that are lighter and might work better in the garden.
I have a wooden ladder that I “inherited” from my parents, and I remember it from my childhood so it’s at least 40 and maybe over 50 years old. It somehow looks to be in perfect shape, and I still use it occasionally, but it worries me. This thread reminds me to replace it.