Just now, johng said:

Ok then  new tap time I think ????

Or replace the cartridge if available. Perhaps even possible to order direct from American Standard, be easier and cheaper than replacing the whole tap.

Just buy a new one, not expensive. In fact OHMPO as Thais call it have some nice new models.Saves a lot of cussing too.

As said getting replacement parts for just about anything in Thailand is likely to be an experience most would prefer to avoid, or forget.  But wish you good luck and hope I am wrong, again.

12 minutes ago, HAKAPALITA said:

Just buy a new one, not expensive. In fact OHMPO as Thais call it have some nice new models.Saves a lot of cussing too.

It's not easy to replace the whole tap. Very awkward to get to where the tap is screwed on without removing the whole sink. So if a cartridge is available or just possible to clean inside the tap, that's a far better way to go if it improves the flow.

1 minute ago, giddyup said:

It's not easy to replace the whole tap. Very awkward to get to where the tap is screwed on without removing the whole sink. So if a cartridge is available or just possible to clean inside the tap, that's a far better way to go if it improves the flow.

Must be different Models, i cant get the lid back on a Kettle, but managed to do it.!.

9 minutes ago, giddyup said:

It's not easy to replace the whole tap. Very awkward to get to where the tap is screwed on without removing the whole sink. So if a cartridge is available or just possible to clean inside the tap, that's a far better way to go if it improves the flow.

Taps are easy to replace with the right tools and the right person wielding them ????

The problem is finding the right person, midget contortionists who can see in the dark & who can also wield a wrench are not so easy to find ????

Last time I tackled one of those  "hot, cold flip up mixer taps"  (really bad flow and leaking)

it had literally been cemented into the counter top ! ended up cutting it off with an angle grinder

then bashing out a  larger hole from underneath the stainless steel sink then had "lots more fun" 

fitting the new tap ????

I don't know any of the 

"midget contortionists who can see in the dark & who can also wield a wrench"  either  ????

 

33 minutes ago, HAKAPALITA said:

Saves a lot of cussing too.

I did a lot of cussing, its best therapy just to let it all out.

2 hours ago, giddyup said:

It's not easy to replace the whole tap. Very awkward to get to where the tap is screwed on without removing the whole sink. So if a cartridge is available or just possible to clean inside the tap, that's a far better way to go if it improves the flow.

I suppose all sinks are not installed the same, but I have removed several times just for this issue and it's no big deal.  Disconnect the drain pipe/trap and putty knife to break the (usually) silicone seal under and it should lift right out.  If the silicone remains attached to the basin, I don't bother replacing.