Grant pump whining and drips from bleed screw

[omits]

Gravity system with Grant pump (UPS 25-60 30). Whining pump but bleeding makes no difference. Now dripping from screw. Questions:
1. Can I remove the screw w/o water pouring out?
2. I have taps either side to change pump. Are they all standard sizes for a new one?
3. Could it be the diverter valve whining?
Thanks.

 

[terryplumb]

Water will come out when screw removed. Close both isolators to pump to reduce water coming out,but will still get some flow.
Threads for pump replacement would be the same,but distance between can be different so check before buying replacement.
Diverter valve ??