Sounds like worn out pump seals
When seals no longer seal, the pump can't prime or hold a prime...Doesn't matter what brand the toilet is, they all require periodic replacement of the seals and gaskets...and eventual replacement of the pump assembly (a whole new toilet costs about the same as a pump assembly). IIt should be done every couple of years as PREVENTIVE maintenance, but for some strange reason, most people prefer to take toilets apart when the bowl is full instead of when the whole system is clean and dry. Eventually, especially if a toilet has been neglected, rebuilding it no longer works...salt, any sand or grit and just plain wear score and scratch the housing so that new seals don't completely seal any more. That's when it's time for a new toilet. Otoh, it also pays to compare the cost of a rebuild kit with the price of an identical replacement. If you can buy a whole new toilet for about the price of a couple of rebuilds, you might as well just ignore it till it doesn't work at all and then just toss it for a new one.