can anyone tell me if the nvld and the purge valve on the 05 pacifica can be taken apart to check for damage? and where is the test port on the 05 under the hood for vacuum testing the evap system? is there a youtube that shows using that port for a smoke test and or pulling a vacuum to see it it holds one?

i have the dreaded p0457 code and i think the p0456? can't remember that for sure. it has been giving me fits to find it. i did a smoke test on the system thru the gas tank fill but that did not show me anything, so i want to see if the test port will do better. and then if i don't see any leaks i would like to take the nvld and purge valves off and test them separately and if they fail i would like to disassemble them to see what might be the issue. could be just dirty and if the diaphragms are bad of course i have to get new part/s. but i do not want to destroy them just in case they are still good and i have to drop the tanks for more testing. thanks