The flow switch on my grundfos UPA 15/90 has just failed in the on
position,

I fitted it in summer 2004, so it doesn't seem long.

Can I replace the switch, AtM I daren't touch it! It'll have to wait till
summer.

Alternatively, should I fit a separate flow sensor. Is there an economic
one that will do the job - if it's an unreliable component I't rather keep
replacing just the switch.

And can the Grundfos switch (if I can get the part), be replaced "dry" or
could a replacement flow switch be fitted dry, or could I get a separate
switch where the electrics could be replaced "dry", like zone valves?

Questions, questions....

Any answers, please?

mike