Weller Piston O-Ring

[2X]

Hello,
I have the Weller SA21A desoldering pump and I his vacuum isn't so power anymore. I bought a new one but I would like to repair and my old one. I measured the O-ring from the piston and the dimensions are below. Do you know if these O-rings are made from some certain material or they are just a regular O-ring? I didn't find any official replacement form Weller. The only spare that I found is the desoldering tip (Part Number: SA21A1).


Inner Diameter: 13,5mm
Outside Diameter: 18,1mm
Thickness: 2,5mm

[PeterG]

That size appears to be a standard size o-ring.

You can source them from places such as this. https://www.oringsandmore.com/metric-buna-o-rings-13-5-x-2-5mm-minimum-25-pcs/