The patent number is 3,716,229. It appears on the bottom of these
instructions downloaded from the Hasbro web site.
This is US Patent record. You will need Quicktime Six to view the patent.
The toy was originally known as the "Springbal", marketed in Europe as
the "Lolobal" and sold by Hasbro, Inc. in the United States as
"Pogobal.". It would appear Hasbro have undertaken court action
concerning the patent.
"In Tech Marketing, Inc. v. Hasbro, Inc., 719 F. Supp. (D. N.J. 1989).
We obtained summary judgment defeating patent ownership claims to
patent of Pogoball toy device."
"In-Tech Marketing, Inc. v. Hasbro, Inc., 719 F. Supp. 312 (D.N.J.
1989) (summary judgment of patent ownership and infringement against a
knock-off of Hasbro's POGOBAL toy);"
I hope this answers your question. If it does not, or the answer is
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soon as I receive it.
hasbro pogo led to their web site instructions.