Hi friends the rear pick up sounded very good until yesterday but suddenly the rear pick up doesn't sound ㅠㅠㅠ
What's wrong with the my base guitar? The front pick-up is working fine..
Bass is MK deluxe model..

This is a picture of electronic components

Just like in 2022 when you were having some trouble, the first thing to try is exercising the pots and switches. Sweep the knobs through their full range about 30-40 times and do the same for your switches. See if that brings your bridge pickup back to life. If not, we can move on to some other tests.

Jimmy J

Next would be to switch the pickup wiring and see if the problem follows the pickup.

The problem was solved by turning the switch and moving the knob repeatedly The rear pickup's starting to sound good
What's the principle?
This method is so magical
I'm Korean, but I'm currently doing music in Japan!
I had a lot of worries, but I'm so happy that it worked out well Thank you! a and have a nice day!

Yay!  Glad that worked! 

If you haven't moved a knob or switched a switch for a long period of time the internal contacts can become slightly unreliable.  I'm not sure why - but think about the audio signal passing through these tiny contact points which are simply held together by physical pressure...  Luckily Alembic uses potentiometers and switches which are sealed and self-cleaning.  You never need to use chemical spray (won't get inside anyway) but simply exercising them will almost always bring them back to the original operating specs.

Jimmy J