Decent pump

Its the pump, I’ve tried what you said and the pressure drops. My solution, get it at the pressure I want by going slightly over and then removing the pump. The pressure stays consistent if there is a good seal. I re-apply the pump to change up the pressure every few minutes and repeat to be fresh blood in my unit.

I have found a Uk metal pump at a great price

I have looked for a quality pump (I am in the UK ) made form steel because I broke the plastic one.All the ones I have found on adult toy sites were expensive or came as part of a kit, but I found one on eBay it was called a (Gunson 77003) Vacuum Pump and I paid £24 + p & p which I thought was very reasonable indeed.some were being sold for £60 + but this one guy is a tool company!

Hope that helps any one in the UK where it’s not always the easiest thing in the word to get enlargement stuff!