Majesty 2014 Stucked knob, chrome Spoiled by rust

I bought a brand new majesty Back in 2014, one year later a lot of the chrome metal parts started to broke in little pieces. Almost all metal parts of the guitar (knobs, switch, tuning keys…). Now I tried to remove the knobs but I cant remove one of then, seems like the knob and the Head of the potenciometer are “glued”.
I am very dissaponted with this issues, but I need to fix the guitar before sell it.
Any idea how can I remove this knob? I need to buy new ones to Substitute, but I only found black in store, but in my guitar they are silver. Here in my country I cant find this parts. 😡