Can spousal support be lowered as a result of reduced income? Our contract was that it would stay the same thru $ ups and downs.

Married 23 yrs. Granted 10 yrs. of support @ $1500/mo. Divorce agreement allowed for 6 month lapse in support (the 6 mos to be tacked onto the end of the 10 yrs) if my former husband were to lose his job, which he did 6 months ago. May 1 payment he was to resume support. On May 1, I rec'd a check for $500 saying it was more than he could afford & because his new job doesn't pay what his longtime job in telecommunications paid, he would be sending me less.Our deal was that support was to stay @ $1500 whether his income went up or down. Do I have to pay for a current income report?p.s.the court ordered him to dissolve a side bus. he had-he told me in a letter that he's glad he never did it even tho it was court ordered bcuz he knew the economy was going to "tank". I think he's hiding income.