Hi Gini,
The hose is 3/4 ID. The stuck flapper issue can only be resolved a limited number of times. The valve is nearing 10 years old and I think the plastic/rubber just starts to get less flexible. I switched to a Whale brand from West Marine since that is all they had in stock with barb fitting of that size. Seems to work just as well.
On a separate issue, I have my Vesper Cortex programmed and awaiting pick up at Rodgers next week, can't wait to start that project! Boat is currently out of the water at the spa getting bottom paint, prop refurbish, packing gland etc done at CSR in Des Moines. With this weather, unlikely I'll see her again until mid January!