I was given one these and it's my first experience with a trainer. It is an original Fluid, as I see the current model is a Fluid 2. After setting it up for the first time I have a couple of questions:

1. When just spinning it with my hand I can hear a faint, occasional fluid gurgle as if the chamber is not quite full. Is this normal or do I need to replace the fluid (or the trainer)? What do I replace it with?

2. This may be related to 1., but when in use it makes a sound a bit like an old siren. Not as loud, but a steady high pitch drone that has a speed dependant frequency. I could not pin point it as nobody was around to ride it so I could listen down near it. This could be tire related, as I put my wifes city bike on it with round but lightly treaded 38mm tires. But tires or not, is that a normal noise?

3. I did not have a front wheel holder. Will I damage something if I don't use one?

Thanks.