You can't do it through eBay.
Instead go to your original Paypal payment. Call PP's Customer Service and ask if they can help you with the rest of your partial refund.
Keep in mind that usually an account is suspended because the seller has been doing all kinds of naughty things.
He still may have some money being Held by PP, however.
And if you don't ask, they can't say yes.
If that doesn't work, and I don't hold out much hope, especially if the partial partial refund was not done through PP, go to the credit card I hope you back your Paypal account with.
Phone the 1-800 customer service number on the back of the card and ask the clerk about a chargeback of the rest of the partial refund. You will probably have to supply proof that the refund was promised. And of course, the clerk will need information about the original purchase, dates, currency, payment amounts, transaction numbers for eBay and for PP. Perhaps the serial number on the money order.
Good luck. This will not be easy.