Oket?

Hello!

I'm American and my Swedish is terrible, sorry.
I'm looking at buying a bike that needs some work, but I can't figure out how to translate a word "oket"... if someone could help, I'd appreciate it!

"Bakre bromskraft ej tillräcklig, Oket behöver bytas och troligen masterpumpen (den vid fotpedalen)"

Thanks!