Mercury XS 250 (Water Pressure gauge issue)

[fish raptor]

My new Bass boat has a 250 XS Merc on it.

1st time out water pressure gauge worked.

2nd time out I noticed after a while (not immediately) that water pressure gauge on Zero although Tell tale was pissing water and no buzzers.

My boat has the actual water tube (not electrical) connection on back of water pressure gauge. It is black in color and I traced it back to motor and it appears to connect to a gray small hose that goes to motor.

Was told to disconnect black hose in motor and and blow light air into hose to see if gauge moves/registers. Have not done this yet.

Also told to look for kinked hose but all looks good.

Question:

Is water coming out of tell tale confirm actual motor is getting water or can tell tale be pissing and somehow water not making it to motor ? Ie. is the tell tale the "end of the line" for flow....

Can I "lightly" blow back on gray hose in hopes of "unclogging" whatever might be blocked ?

Was thinking of disconnecting the black horse inside motor where it connects to gray hose and running motor with ear muffs to see if water peed out end of gray hose ?

Can anyone give me an info on what steps I can try to resolve problem ? Any help would be most appreciated. I could take it to dealer but it might be something super simple and happen down the road and I would like to be able to try to solve myself.

Motor only has 100 hours on it.