Dents on a Trumpet Piston - Repairable ?

musicalstash

Can any brass players / repairers  help me out . 

I picked up an old  Conn Trumpet which has one dented piston so does not fit in the shaft of the trumpet . 

Wondering are the pistons repairable or interchangeable ?  

Thanks

Mellish

Try Brassrepair.co.uk or Brass-Fix UK