Broken oil reservoer cap, how do i get a replacement?

Are you aware they are no longer in production?

Find it here (probably "NLA" or "Back Ordered"):
Over the years the size of the cap has changed. There is only one cap available and replacement tanks to fit the current are NLA everywhere. I suggest you talk to a living breathing human on this, it may save a headache later.
Remington.com
http://shoppingcart.msservicecompany.com/Default.aspx
• Type "YourModelNumber" into the "Search for your unit by Model:" window, then click search.
• Click the “YourModelNumber” - Remington Electric Chain Saw "View Model" link.
• Click “View Owners Manual” or "View Illustrated Parts Diagram" link.
• Type "YourPartNumber" into the “Search for your parts by Part #:” window, then click search.

If "NLA" or "Back Ordered" try here.
Master Distributors
http://www.masterparts.net/remingtonelectricchainsaw.html
There was a 3 pack available the last time I checked.

If you have more questions or need additional help please reply below and I will get back to you. HTH & Good Luck.
Lou
Thank You for using FixYa.

"Campbells Supply" can get them. It is where I got mine and it works perfect.