Missing o ring where can I find one

Sounds like it,either the float is stuck,badly adjusted,the needle could be worn,the needle seats o ring may be leaking around the edge,there could just be a bit of dirt in it stopping it from seating properly.

Check if the bowl is cracked. If so, it's replacement time.

follow this steps and fix it. God bless you
f a faucet leaks, replace seals and gaskets . If a shower head leaks, create a better seal or replace seals.
If a sillcock wears out, replace the washers .
If a compression faucet drips from the spout, replace the washer and/or the seat .
If a faucet leaks from the handle, replace O-ring(s), replace the packing washer, tighten the packing nut, or replace worn packing, depending on the valve type .
If a ball or cartridge faucet leaks from the collar, replace worn O-rings .
If a disk faucet leaks around the base or has reduced flow, replace cracked or pitted disk assembly or worn inlet seals .
If there is water under the sink, tighten the faucet-set locknuts under the sink. You also can replace putty or a gasket, replace a worn faucet, or replace leaky supply tubes
If the aerator leaks around the edge, replace the washer in the aerator
If the spray hose leaks or has reduced flow, replace the O-ring on the diverter valve, replace a worn washer at the base of the spray head, or clean the diverter valve and spray head

make this steps and fix it. God bless you
f a faucet leaks, replace seals and gaskets . If a shower head leaks, create a better seal or replace seals .
If a sillcock wears out, replace the washers .
If a compression faucet drips from the spout, replace the washer and/or the seat .
If a faucet leaks from the handle, replace O-ring(s), replace the packing washer, tighten the packing nut, or replace worn packing, depending on the valve type.
If a ball or cartridge faucet leaks from the collar, replace worn O-rings .
If a disk faucet leaks around the base or has reduced flow, replace cracked or pitted disk assembly or worn inlet seals
If there is water under the sink, tighten the faucet-set locknuts under the sink. You also can replace putty or a gasket, replace a worn faucet, or replace leaky supply tubes .
If the aerator leaks around the edge, replace the washer in the aerator
If the spray hose leaks or has reduced flow, replace the O-ring on the diverter valve, replace a worn washer at the base of the spray head, or clean the diverter valve and spray head

make this steps and fix it. God bless you
f a faucet leaks, replace seals and gaskets . If a shower head leaks, create a better seal or replace seals
If a sillcock wears out, replace the washers
If a compression faucet drips from the spout, replace the washer and/or the seat
If a faucet leaks from the handle, replace O-ring(s), replace the packing washer, tighten the packing nut, or replace worn packing, depending on the valve type
If a ball or cartridge faucet leaks from the collar, replace worn O-rings
If a disk faucet leaks around the base or has reduced flow, replace cracked or pitted disk assembly or worn inlet seals
If there is water under the sink, tighten the faucet-set locknuts under the sink. You also can replace putty or a gasket, replace a worn faucet, or replace leaky supply tubes
If the aerator leaks around the edge, replace the washer in the aerator
If the spray hose leaks or has reduced flow, replace the O-ring on the diverter valve, replace a worn washer at the base of the spray head, or clean the diverter valve and spray head

follow this steps and fix it. God bless you
If a faucet leaks, replace seals and gaskets .
If a shower head leaks, create a better seal or replace seals .
If a sillcock wears out, replace the washers .
If a compression faucet drips from the spout, replace the washer and/or the seat .
If a faucet leaks from the handle, replace O-ring(s), replace the packing washer, tighten the packing nut, or replace worn packing, depending on the valve type .
If a ball or cartridge faucet leaks from the collar, replace worn O-rings .
If a disk faucet leaks around the base or has reduced flow, replace cracked or pitted disk assembly or worn inlet seals .
If there is water under the sink, tighten the faucet-set locknuts under the sink. You also can replace putty or a gasket, replace a worn faucet, or replace leaky supply tubes .
If the aerator leaks around the edge, replace the washer in the aerator .
If the spray hose leaks or has reduced flow, replace the O-ring on the diverter valve, replace a worn washer at the base of the spray head, or clean the diverter valve and spray head .

Normally they're held on with 2 wire rings, 1 at the edge of the seal at the door opening and the other on the edge of the outer drum. Unplug your machine and remove the lid, this will help access and give you more light to work with. Remove the ring at the door opening first and pull seal from the lip. Access can now be made for the one at the drum. Do the same for the one on the drum.

When putting in new one reverse the procedure and start at the drum, make sure you have the seal the right way around, normally holes in bottom of seal for drainage. Thread the seal over the lip and then put ring on. Same process for the front. Put lid on and plug machine in and test for leaks.

Normally they're held on with 2 wire rings, 1 at the edge of the seal at the door opening and the other on the edge of the outer drum. Unplug your machine and remove the lid, this will help access and give you more light to work with. Remove the ring at the door opening first and pull seal from the lip. Access can now be made for the one at the drum. Do the same for the one on the drum.

When putting in new one reverse the procedure and start at the drum, make sure you have the seal the right way around, normally holes in bottom of seal for drainage. Thread the seal over the lip and then put ring on. Same process for the front. Put lid on and plug machine in and test for leaks.

There is an o ring that seals the valve that is operated by the trigger. It sounds like this oring is defective, or missing. Home depot or lowes should have no problem returning this for you if it is less than 90 days. it is fairly complicated to disassemble.

Unscrew the retaining ring that holds the aerator and "O" ring. Note the O ring may be made out of brass or rubber. If brass it must be inserted with the beveled edge "in" Replace the retaining ring, sealing the threads with a small amout of plumbers putty or teflon tape. You can get a a repair kit which contains everthing you'll need for a couple of bucks at most hardware stores.