Vortex Sound Research

This question is posed towards anyone that has some experience repairing synths. I'm quite new to it, but a close friend of mine gifted me with an Alpha Juno-2, and a few of the keys are somewhat non-responsive. I'm thinking about ordering a contact strip for that section along with a new battery and some other components, but I'm wondering if it's better to order the entire 12 note strip, or can I just order a 4 note strip, and just replace that one section? The non-functioning keys are the 3 bottom/left-most keys.

TIA for your advice!