An inability to find therapists to work at a Turkish baths is partly why a council is "significantly below budget" this year, a report said.
The council-run venue in Harrogate, North Yorkshire, is described as "Britain's most fully-restored Victorian Turkish Baths".
But the number of empty treatment rooms in the building has prompted concerns over a loss of revenue.
Harrogate Borough Council is now planning a recruitment drive.
An update on the council's financial position showed empty therapy rooms at the Parliament Street baths had seen a serious loss in income.
The Turkish Baths opened in 1897 and the council took over their management in the late 1990s.
It has a health spa with a range of treatments but faces growing competition from hotels and other treatment centres.
The report to the overview and scrutiny committee pinpointed an income shortfall at the baths as one of the keys reasons behind a forecasted council overspend of £373,000 for the quarter, said the Local Democracy Reporting Service.
Part of the loss of income stems from the vacant therapist positions, the report said.
"This forecast reflects a shortfall of income of £295,000 because the facility was closed for 10 weeks for refurbishment rather than the budgeted four weeks, together with a significant underperformance in massage and beauty income due to the inability to recruit therapists," the report states.
Therapists can earn about £18,000 a year at the baths.