Sprung bass key. Key sticks upwards from the keyboard. How do I fix this? This is on a Casio PX500L player piano.

ask casio directly or GOOGLE it

https://www.casiomusicforums.com/index.php?/topic/19061-broken-keys-of-privia-px-120/

https://www.youtube.com/watch?v=lREFbtqDr90

https://100tutos.com/video/1664158/how-to-repair-a-stuck-key-on-a-casio-px-120-digital-keyboard/

https://thehub.musiciansfriend.com/keyboard-buying-guides/pianos-and-keyboards-how-to-choose
https://www.amazon.in/Keys-Keyboard-Electronic-Digital-Piano/dp/B005N0AML4
https://www.amazon.com/Casio-CTK-720-Key-Musical-Keyboard/dp/B000V0CU6G
http://web.mit.edu/~ecprice/Public/freq/googlelist.counts
http://www.archive.org/stream/NEW_1/NEW.txt&ld=20140121&ap=2&app=1&c=uk.dogpl&s=dogpileuk&coi=239138&cop=main-title&euip=65.55.52.108&npp=2&p=0&pp=0&pvaid=0ecbb68aa2494234817f86c47110b9e9&ep=2&mid=9&en=qD9Z4iWOaaPlhngGE2dCw8AB6g1YUAk6exyPXtpCYBrFbShTfF8rj

is it under warranty ?
if not
you may have to contact your point of sale to find their local repairer

if you cant un stick them yourself that keyboard will have to be taken apart

are the two keys ... white keys or black ...nearby or way apart
do the two keys drop loose..and lift up
or stay down
example will vacuum cleaner suction help lift the stuck keys or not

sales blurp says this
A spring-less hammer system
Scaled Hammer Action Keyboard

https://www.jbhifi.com.au/musical-instruments/casio/casio-cdp-120-digital-piano/91120

Old reply so hopefully it's fixed. Dust or hair can get through the gaps and land on or near the contacts of the electronic key sensors. To be on the safe side (rather than doing a diy) take it in to the technicians. They'll have it fixed in a jiffy

Hi,
I’m repairing a casio cdp-220r for the same reason. The F3 key does not sound at all and some adjacent keys sound louder than the rest at normal play attack. I will have to replace the entire octave memebrane as I found that it was broken when I finally got access to it. See phot

Verify the sound in headphones directly from the unit. The cymbal MAY be panned to one side or the other and will require higher frequency response than some of the piano notes.

You hold down the function key/button and then use the PIANO keys with the "tempo" shown above them.
In that section of the keyboard, the C# key raises the tempo and the C key lowers it. You can also use the numbered keys in that section to dial up a particular value. Hold function down and strike the numbers you want then release the function key/button

I don't believe there is an adjustment for loudness of the metronome other than the overall loudness of the piano..

with mixing, get the bass right, then add the piano/pad sounds then bring up the drums til it sounds good.

In Casio Chord mode, the bottom keys up to the second F plays Bass Chords. The Keyboard is just putting the keys you play back into bass when you get up that high. If you read along the plastic edge above where they keys come out of the keyboard, it shows you where the Chord keys end and the Keyboard begins. If you want use of all the Octaves, slide the power switch to the first setting (normal).