TBH if it’s too heavy to enjoy playing, just move it on. Just because it’s old doesnt make it perfect for you
Playing a bass you don’t enjoy is like marrying a person you don’t love and refusing to divorce them
I love playing my cheapie Vintage Stingray clone, it’s as light as a feather and it’s plays itself (almost), like buttah, as they say. I wouldn’t sell it ever. Go figure.