Simply put, we need more details. There are hundreds of Bunn models, both residential (which we don’t assist with here) and commercial (which we can assist with).
Look at your coffee machine. it should have a data tag of some kind on the unit. It will have model information that we need to help you.
If you have a home unit, there are not any replacement parts that you can acquire, besides the glass decanters and maybe the plastic filter housings. But no internal parts. The cost of service often outmatches the cost of full replacement of home models. Such is the nature of small home appliances, sadly.
Without more details, this is as much information as I can provide regarding Bunn springs: