Yamaha csr-170: loose key

One of the black keys in the digital piano I bought second hand for my kids is loose and moves left to right quite a bit more than the others. It plays just fine.

Should I replace it and if so how complex and how long would it take me?

Not sure if it is one of those things where it is destined to break more so if so I should at least have the parts on hand.

You sure this is a CSR-170 - no such thing made by YAMAHA ?

My bad. It was a typo. Should say csp-170.

I’ll see if I can update the topic.

I am guessing the key itself may be cracked or broken where it connects and pivots at the back of the key. A new key is available here:

Style 122W key, black note - Syntaur

Hmmm … I think the Guide Cap has come off. Each key has a guide post associated with it, each guide post has a Guide Cap on it that just sits on top of the post held in place by two minute clips. They are covered with a Silicone Grease. If the grease dries out that cap can get lifted off and then either falls into the base or getting stuck inside the key.
Once the Guide Cap is gone the key is very floppy left/right but plays OK.
A lot of work to fix; entire keyframe has to be removed, then white keys either side of the offending black key have to be removed and then the black key removed to get access to the guide post.
To remove keys a thin blade type of thing needs to be inserted where the little arrow is on each key to release the respective key.