Very likely - if it's sticking open [as they do, when they get gunge buildup on the poppet valve stem, or a hole in the diaphragm], you will get reduced/no compression.

Have a look at the deco valve diaphragm chamber - if it has 3 spring clips around the periphery, it's rebuildable; kit is available from the ODK Shop. If not, it will need replacement.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."