The first thing to check is the order: the gasket should sit on the jar edge, then the blades, then the retaining ring. Per the directions when changing an automotive oil filter it will work best if you put it together while all the parts are wet because that lubricates the rubber. One problem I’ve seen is that there can be a build-up of material on top of the metal baseplate of the blade assembly so it’s not smooth anymore. Just scour that off until it’s smooth, also the bottom edge of the glass jar. But the final show stopper in my case after spending half an hour on those is that the seal which fits around the shaft in the blade assembly wears enough so it starts to leak. I don’t think there’s a fix other than replacing the blade assembly, but having a spare, maybe meant for a different purpose is good because swapping them is a quick thing to try. We happened to have a milkshake blade with little wear, putting that in stopped the leak. The seal is made to tight tolerances but if you can feel a little...

Some models do, some don't. On a Fire 10 HD there's a little cover on the right edge you can pry open with a fingernail, it's inside that. On other models it may be somewhere else, investigate anything that looks like it might open. But even if it has it, on an Android phone there are some apps that can be moved to SD and some that can't. I did find that having a lot of old pictures (screenshots and from the cameras) eats into the same space available for apps. You can move them to SD with a file manager program, then put the SD in a reader and move them off to someplace where storage is cheap, like a blank DVD.

5th generation, sure, but not the original. It's the fastest and most reliable way to transfer files on and off it, shut it down and put a card in or take it out. With ES File Explorer, maybe some others, you can transfer over bluetooth or WiFi or USB but it's slow. I've had a 128 gig card in and out of a Fire 10, works fine.