A few years later and now I am in the same boat - got a beaten up RH750 and need to replace the broken buttons. No support from TC Electronics anymore so trying to find the spare parts. Do you have a part number or how did you find them Matlevo12?
It doesn't look like Malevo12 has been around anymore since 2020. You could try contacting a TC Service Center directly and see if they can help you with parts. There are two somewhat near you in Las Vegas, NV (Neon Production Supply, 702-912-4330) and Montebello, CA (Digitron Electronics, 323-887-0777). Good luck.