I have not tried to replace the microusb charging port, but in reviewing the [http://h20565.www2.hp.com/hpsc/doc/public/display?sp4ts.oid=6943779&docId=emr_na-c04493466&docLocale=en_US|Maintenance and Service guide] documentation for the microusb charging jack, it is part of I/O board, identified by part number 761971-001 on page 8. You can also see this part on the [http://www.hp.com/hpinfo/globalcitizenship/environment/productdata/Countries/_MultiCountry/disassembly_notebo_2014732346117.pdf|Product End of Life Disassembly Instructions] as well.
The [http://partsurfer.hp.com|HP Part Surfer] does not list it as available for purchase, but you may be able to find it through an [https://parts.hp.com/hpparts/Part_Resellers.aspx?mscssid=96122EBD3298436A832030A465E2AB1F&geo_code=NAHP|Authorized Parts Partner].
However, since this is a micro usb charging port, I would approach replacing the port itself no differently than you would a phone or tablet.
In the process of searching for your answer, I found [https://www.youtube.com/watch?v=TUjaxHSGSPk|How to fix the Hp Chromebook 11], which identifies the connection between the motherboard and battery connection as a cause where the Chromebook itself does not show that it is charging.
Since you have several, I thought it would be a good start to verify that the ports are not working before replacing them.
If you have to change the micro usb receptacle, it is a USB Micro-B. You can find the [https://en.wikipedia.org/wiki/USB|USB connectors mating matrix] on Wikipedia to verify.