Can I change only the Hydraulic pump?

[Mosqui]

A newbie here

I have a set of Hayes nine in my bike and they are not working very well, looks like air gets into the system.
Can I only change the pumps? Are all the other items able to work with another system?
Or I need to change everything?

Thanks for your help

[Duck!]

Change everything. The Nines are quite an old model, and rather prone to clogging if the fluid has not been bled regularly.. Additionally, levers and calipers are designed to work as a system, and it's not recommended to mix different brands of levers & calipers.

[Mosqui]

thanks for the advise.
Any recommendation on a budget? I just use it for commuting, not interested in nothing fancy

cheers

[Duck!]

Something like the Shimano M315, M395, MT200 or MT400 will do the trick.