Long time stalker, enjoy reading all the interesting bloggs and stuff on here but never posted, however I am wondering if anyone knows if its posisble to reset a Manometer to 0?

I have a Sevylor Yukon, and have broken it out again now that the weather is good after being in storage all winter. However my Pressure gauge seems to now be stuck at 0.5 ish and was wondering if there was anyway of resetting it. I can obviously work out the difference however I am unsure if its actually telling the right pressure even accounting or the difference.

It has 2 screws, and i do have an in-line pressure gauge that i recently brought however I am unable to use this on all my chambers so i need to use this plugg fit one, if anyone knows if its possible to reset these id be grateful, otherwise i will have to fork out for a new one!