failing shower/bath pump advice

I have a pump in my airing cupboard which provides adequate water pressure to taps and showers in my house.It pumps both hot & cold. A seperate system feeds non pumped sources like toilet cisterns etc.
The pump cuts in when you turn on a tap and is about 2 1/2 years old.
Recently the pump has stuck a couple of times though appears to have sorted itself. I have also noticed that the sound it makes has changed and seems more rattly. It sits on a paving slab on 4 sorbothane rubber feet (from an old trainer insert) which has always provided a degree of noise and vibration deadening.
Q: Anybody know how long these things last ?
Q: Are there any replaceable components i.e prushes or impellors ?
Q: It looks as if I would have to remove the whole pump if something went wrong, which I guess would involve switching off the water and draining the whole system which would be a lot of work. I wondered if any components can be serviced in situ. The model is a SALAMANDER RIGHT RHP100
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