Scubapro MK25 Piston

[Mare Nostrum]

Hi,
My MK25 is around 7 years old and the last time I serviced it I got unstable IP readings. It starts at 140 psi then creeps up to 152 then down to 148. Creeping up happens in minutes but it takes more to get down to 148. I donno if that is a Piston issue. I tried changing the HP Seat but same thing happened.
Any suggestions? And if it is a Piston issue where can I get it from?
Thanks...

 

[snowdog61]

look at the sealing edge of the piston for radial scoring under high magnification if you can - you likely have some damage which is causing the erratic behavior. You can buy a new piston or repair the one you have using multiple steps of very fine abrasive paper and micropolishing the edge. There's a great tutorial by one of the reg guru's on this board - can't remember the title but M25 piston should get you there. It's here and worked great for me on a piston that had the same issues.

 

[snowdog61]

Found it. Try Here.

 

[Mare Nostrum]

That looks great buddy. I'll go through it and see what I can do.
Thanks loads...