Pool Pressure down, air in pipes..help!

Hello all - ok ..so Ive been on a mission to locate my trouble. Im getting a fairly good prime but a lot of air bubbles in the return jets & obviously I have a suction leak is my guess..here's what I've done :

Water level is fine , half way up skimmer intake & door is not stuck to skimmer
A. Cleaned Cartridge filter (although cartridges are getting old) Replaced large O ring on filter.
B. Replaced all (3) O - rings on water diverter valve and Ring & lid on pump pot replaced.
C. Flushed out impeller & skimmer line with bladder hose attachment , seemingly clear.
D. Soapy water to various areas of above ground pipes reveals nothing. No union between pump & pipe, just caulk.
E. Barracuda hoses have no leaks ...no obstruction of debris.

Barracuda not moving , I only get 50% of 1 on the gauge reader...should be 2 .

PSI pressure gauge on cartridge filter reading steadily in between 1-2 KG/CM.

I do have solar panels? Not sure if they are causing anything , I do hear a suction squeak when filter turns off...assuming thats just water getting sucked back in opposite direction.

I did a skimmer test of water level. Little less than 1/4" evaporation in 2 full days ...but its still kinda cold at night 55degrees , 70 in day & I have a cover...

Last resort which Im not to keen on is hiring a leak detection company .. but my deck is all variable sized pavers and it will ruin the look to dig for some underground broken pipe!

How do you know if your pump is old & needs replacing / not pulling the load? Mine is a WhisperFlo pre 98 , pretty old!

Doesn't seem like an underground break bit at this point I think I've exhausted all avenues? Any clues appreciated...thanks!