It doesn't sound good. You may want to verify that the front (driven pulley) isn't starting to split and that the brake does not drag. (The disc will get very hot with out using the brake.) What is the model #? 917XXXXXX

917.272201 is the model. Bought in 2000.

917.272201 has a hydrostatic drive transaxle! Most likely scenario other than brake dragging/seized is that the transaxle oil has deteriorated past being stable in service.
Changing the oil will probably return the performance to near OEM quality.
A good synthetic 20 W 50 oil is recommended. Capacity of oil for this unit is 78.8 ounces (or 2.5 quarts).
The troublesome part of this rehab lies in the fact that it is often necessary to remove the transaxle assembly from the chassis and turn the transaxle upside down over a drain pan or bucket to remove the old oil.
Not an impossible task (has been done many times) but the level of mechanical expertise of the person doing the job will determine how easy, or difficult, the task is for the individual.

If you conduct a search in this forum using key words (and different combos of words) pertaining to "changing hydrostat oil" you will find a good base of info to work from.
Some threads might even have a post outlining in detail the steps needed to do the job.
"Search" is found near the bottom of the tractor forum opening page

Here is a link that might be useful: 314-0510 IPL

Before trying to change ther oil, I would reccommend checking the level. There should be what looks like a garden hose (the vent) attached on top-rear of the trasnmission. Pull this hose out, (you will need plyers to loosen the spring ring); use a pencil or any clean stick to measure the oil level; it should be approximatly 3/4 inches from the top; if it is lower I would just add some 20W50 oil. When you pull the pencil/stick out you will also be able to look at the oil on the stick and determine if it is cooked.

On my mower (1997 46"deck/Yardmachine), and on my son-in-law's (mid 1990's Craftsman 42"), this solved the problem!!!