Blackwidow Ultimate 2014 duplicating letters

Hi, I have an ancient Blackwidow Ultimate 2014 and recently it has been duplicating some keys. It started with only 't' but sometimes it duplicates 'k, a, s', and others more rarely. I've already cleaned under all the keycaps and apparently am already on the last firmware possible. I tried installing Razer synapse 3 as I saw in another thread but, it doesn't support the keyboard, and can't find any solution online by myself. Is there a solution to it? Aside from this key duping, the keyboard is in great condition and works really well. Thanks for your time