No telltale on 1987 Yamaha 200

I have boat at yard , hooked up to water source but no telltale. There is no water getting up to the power head. Where might it be plugged up?

Is it overheating? How do you know water won't make it to the powerhead? Try removing the telltale hose from where it plugs into the block and see if its a clogged hose or what.