National is a Panasonic marketing brand, so yes, it is an early Panasonic e-bike. No internal motor spares have ever been sold for these units.
One correction on a comment above, Panasonic didn't take over Matsusbita*, Matsusbita* changed their name to that of their top brand, Panasonic.
Panasonic/Matsusbita* are in turn owned by Matsui Holdings whose major shareholder is Philips, the Dutch electrical giant. Product marketing is under the names Panasonic, National, Technics, Matsui, Sanyo and other names. Sanyo were the group's most recent acquisition.
* N.B. In the Matsusbita name each time above I've changed the "h" to a "b" to prevent the spelling censor from deleting the offending part of the word.
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