How weird! Maybe something fell into it if there’s nothing loose.
Electric upgrade is good (fitted a Davis Craig). To have it as a ‘puller fan’ without swapping the mechanical water pump I had to move the radiator forwards around 1” which was fairly easy task and uses the same hoses.
I find it’s on a fair bit in warmer weather so like Panky I’m plumbing a KTM250 mini rad on a control valve that should make it come on less and allow me to control cooling in all weathers.