If I understand correctly, you filed to garnish wages, and your ex has either requested a hearing pursuant to the garnishment, or a separate OSC to modify spousal support. Your ex's original order was 10% of his gross income. So, even if the court agrees that he cannot pay you the original order, he would still owe 1/2 of the order, because federal law permits up to 50% of disposible income as a garnishment for support, and after taxes, $1,250 would only be 40% of his income.
So, legally, your ex can still pay the order, and there is no reason why the court shouldn't continue to order the payments.
The other avenue for you would be to prove that your ex is intentionally underemployed. This may or may not be the case, because the job market isn't great. But, if you suspect that he is intentionally underemploying himself, in order to avoid paying support, then you may want to try to prove that there are jobs within his talent and capacity that are available, and there is no reason why he should not be seeking work.
In short, there is no reason why your ex cannot pay the original order, even with only one third of his original earnings. That's what you must emphasize to the court. And, your secondary argument is that he can earn more, but is hiding behind his spouse's earnings.
If you really want to win the secondary argument, then you will need a lawyer, because proving "earning capacity," rather than actual income is very difficult from an evidentiary proof standpoint.
Hope this helps.
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