When to start worrying about the COOP Mortgage?

They should be looking into refinancing now when the rates are low. Of course there may be certain clauses in their existing loan which is causing them to hesitate. But nevertheless the pluses of refinancing could out weigh the negatives, but I would certainly want to ask them about this.
E. S. Funding Co.
Licensed Mortgafe Broker NMLS#60631 since 1990
Licensed Real Estate Broker

There's almost always a prepayment penalty, so may be better for the co-op not to refinance now.

$190,000 per one-bedroom is a hefty mortgage. Accountants like to see less than $50,000. It'll cost you ~$190,000 less than the same apartment in a mortgage-free building, of course.

Oops, make that "less up front". You pay the interest on the $190,000 whether it's via your share loan or the co-op's underlying mortgage.

One has to do the numbers. Avoiding a prepayment penalty could end up costing the co-op much more.

"It'll cost you ~$190,000 less than the same apartment in a mortgage-free building, of course"
I disagree with this. Based on the usual market preferences (and people's aversion to higher maintenance Coops) I think it will cost you a lot more than the $190,000 less in purchase price.

30y, you contradicted yourself. You are saying that people do not like high maintenance. If so, they should want a bigger discount than $190k. Is that what you meant?

I lobbied hard to get our building to assess shareholders ~$100k each to retire the underlying mortgage. Nobody wanted to write the check, even though it would have cut maintenance by a third.

"Why should the next owner get the benefit?" was the usual response. Lots of skepticism that buyers would pay more. Instead we refi'd the mortgage and kept the lawyers, appraisers, and banks happy.

Flare, paying down is hard as some shareholders have limited ability. If coop has excess cash, it is much easier.

Tenants could have borrowed the money at a lower rate than the corporation.

30yrs is right that the deterrent effect of the higher maintenance can be more than the math warrants.

E.g., at 5% the OP's maintenance would be $625 higher than in the same co-op next door where the share of the underlying mortgage is, say, $40,000 rather than $190,000.

$625 more for an ordinary one-bedroom might well knock more than $190,000 off the price the seller could get in the next-door co-op.

Some of that's fear of higher maintenance now, and some of it's fear of much higher maintenance later. If the OP goes for higher price and lower maintenance, she's borrowing for 30 years at a low rate. The co-op with the huge mortgage, though, can borrow for only 10 or 15 years, and the shareholders can be really squeezed if the co-op's re-fi is at a much higher rate.

In some co-op markets (DC, I think) the advertised price is the total of cash and share of underlying mortgage, so buyers know what the story is without digging into the financials.

"a lot more than the $190,000 less in purchase price."
I think that is stated correctly.