I have a Jado bathroom faucet that has a restriction in it. Is there a screen that I need to clean?

If he knew how to disassemble the faucet but it was corroded so badly it would not come apart<?>... sometimes a Dremel with cutting wheel is the only option.

If he wasn't familiar with "JADO"... ask JADO to help identify your faucet.
http://www.jadousa.com/default.aspx?aspxerrorpath=/searchResults.aspx

Get the technical documents yourself and then find a different plumber.

Depends on the type of handle. If you have both hoe and cold handles they can usually be removed by prying off the cap that has "C" or "H" on it. Under that there will be a Phillips screw.
Single handle have hex key set screws on the back or under side. Use can back that out with an "Allen" wrench.

Sounds like you installed the cartridge incorrectly. The orientation is important to note when removing the old unit. Try pulling it out and reversing the orientation. Check the inlets and match them up.

The specs say that there are two check valves but the diagram does not show them. Take the weight off the hose and see if it is causing the restriction. If it is not, what is the water pressure in the house? The 2.2 GPM is the maximum flow rate.

Check the screen in the end where the water come out it could be plugged.

http://www.jadousa.com/products/productDetail.aspx?id=3582

exploded diagrams:
http://www.jadousa.com/assets/documents/jado/parts/Parts_3794.pdf

Assuming I have the right product, (Is this it? 816/003/144) This should help. see step 3
http://www.jadousa.com/assets/documents/jado/install/Install_4040.pdf

the washer/and or seats are not properly set and as water rushes in its forcing its way thru seat washers and creating whistling noise

you have to locate the water shut off valves before you attempt removing the water lines, hopefully they will be located on the lines under your sink, if not you will have to shut the water main off coming into the house. After you have shut the water off and disconnected the lines, look under your sink at the back were your faucet comes through the sink and you will find the fasteners, unscrew these counter clockwise and the faucet will lift out .

Jado are ceramic disc cartridges no washers you should replace both sides.You need to remove the handle and unscrew the cartridge

Here is a link to the repair parts page on Jado website for your faucet. Exploded diagram shows how the thing goes together...

http://www.jadousa.com/assets/repair/842001_repair.pdf

The handle assembly and collar (8) will thread off after pushed past the limit of the cartridge (gentle consistent pressure)...

In terms of leak itself its hard to say but if the faucet froze from sediment build up and is now leaking it is likely that part of the cartridge is 'clogged' open...

Hope that helps...