I have a bodge job my current GPU, one fan failed and another seized up, the third one worked but was taking all the slack. Went with a deep, careful clean and oiling up the fans(turbine oil), left it for days to dry out but ended up no better off. Was going to go down the route of sourcing some replacement fans but decided to remove the shroud(leaving the heatsink in place) instead and cable tie on spare 140mm case fans(they're a bit too big, but work) which i've hooked upto the case's fan controller. My only regret is not having done it sooner, the GPU runs quieter and cooler now than it ever has.
I honestly wish GPUs could move to a more standard and universal fan setup that allowed people to swap out the fans more readily/easily with whichever they choose and used a more standard fan connector.