Oh yeah, I had even forgotten that alarm existed (is it even used in the current THZ?). What I do remember is that the original alarm sprite looked like total trash, and yours is, without a doubt, a major improvement over the original one. I'm not that good with glass related sprites, but I looked up alarm buzzers, just to be sure.
I'm well aware that the sprite probably has a different alarm buzzer design than in these photos, but comparing these pictures to your sprite, I can say that the little shines that you've made on the right of the sprite could use some toning down, and would probably look better with just a few, or just one). As for the bigger shine on the left of the sprite, I noticed that it seems a bit too straight, even when on the rounder bottom of the glass-- so that being said, you could probably round the shine line in there around the bottom of the sprite, and maybe tone it down a bit, as it starts to reach the bottom of the glass. Still, that's a really darn decent sprite, well done.
As for the spring, without a doubt, it looks a lot better than the previous one you had, and the only problem I can see in here is the spring part in the middle of it in the animation. To try to explain it, it seems that the bottom half of the spring stands mostly still, while the top half of it is moving upwards, so you might want to make sure that the entire spring in the middle of the sprite moves along slightly, for the sake of consistency in the animation.
And a little tip for the gif animation, you could try animating it similarly to how SRB2 does it, by making the spring directly stay on the highest height of the animation the moment that it's touched. Here's a demonstration of what I mean:
The going up/down transition frames works better for when the spring is going back down. Keeping them out of the first half of the animation gives a better impression of quickly launching the player upwards.