I think I may have overfilled my boiler...

Last Saturday I went to check the water level in my boiler, and flush the low water cut-off. I am 73 and recovering from 2 knee replacements, so I hadn't been in the basement for months because I couldn't get down the house of horror stairs safely. Only a little water trickled out when I pulled the low water cutoff lever. The heat had come on that morning, and I had hot water (hot water is off the boiler). So I assumed the boiler must be near empty since it hadn't been checked regularly for most of the spring and summer.

In February, during annual maintenance the technician noted that the glass was pretty dirty and it was leaking at the bottom and should be replaced. He also fixed my automatic water feed. However, it only worked twice and then crapped out again. I don't trust those; twice I had near disasters when it malfunctioned and started to overfill. For the last few years, I have been checking the water level weekly and filling manually as needed.

I am noticing a bit of a rumbling sound sound when the boiler is running. My radiators are hissing more than normal. But several radiators are not getting hot. This morning the glass looks different, like it may be full of rusty water. I let a bucketful of water out, but still could not see the water level. After the bucket cools, I'll empty it and take some more out. I read that there is a pencil trick to see if the sight glass if actually full. I don't have a good way to get a lot of water out of the boiler. I'm not sure what the technicians do. They might be somehow dumping into a main drain somewhere. Since it's too hard for me to carry the bucket upstairs, I just usually dump it in the dirt crawl space, or, it just evaporates between times when I flush the cutoff valve. Any suggestions until I can get the guys here and get the glass replaced? Although the boiler is 21 years old, the technician commented that it was a very clean system and in good shape. Thanks for your help. You folks have helped me a few times over the years.