The old site that you were referring to was that run by the Springfield Research Service. At that time it was run by Frank Mallory. Mallory died several years ago. The enterprise was sold and the current owner no longer allows this data to be posted on the net. It is a for profit enterprise. You can submit a request to the current owner and it will eventually get checked and a fee charged if and when something is found. The process is not built for speed or economy.
You best bet is finding someone with the 3 published volumes of serials that SRS published whom might be willing to check your number. Those volumes have the great majority of numbers in the SRS database. Be aware that finding a hit is like the proverbial needle in the haystack.