some buttons never flash

[garma]

i dropped my sp-303 and it's damaged..
then some of buttons never flash..
before i dropped, it worked perfectly
back C,D and reverse, loop, gate
these buttons works..
just red light dosen't flash when i'm using
so..how to fix it?? i just try to open it up
but i'm not sure i can fix it
i don't know anything about "MACHINE"...

so..anyone who has experience like me..
please give me a advice!
thank you!