Accumulator Pressure Low, no loss of braking?

I've read through plenty of the other forums trying to match my problem to their low accumulator problem, but nothing quite matches up to my symptoms. I have the vehicle listed above SR5 with roughly 250,000 on it. Previously I had the brake alarm, abs light, and traction control light come on and got the typical "accumulator pressure low" code with my Autel scanner. That went away after about a day about 30k ago, but now it's back and no sign of going away. I have hard brakes and no mechanical problems (just drove 7 hours), but the error is there with the alarm and all. The motor for the accumulator is running and the accumulator appears to build pressure with no obvious signs of leaking. However, the accumulator motor cycles frequently and at the end of some of the cycles it ends with a screeching, kind of sounds like a goose in an odd way. Everything I've seen online, there's normally a loss of braking power or some other symptom that points in the right direction, but I am officially lost and asking for any help. I've checked fluid, bled the ABS system, bled the VSC system, and did a standard brake bleed as well.