I have 3 SVT right now. It's my favourite rifle. It's great rifle, but requires tuning with gas port, good cleaning and oiling, and making sure that gas port piston works. It is quite accurate (that's why it was made as sniper) and has light recoil for semi in such large rifle caliber. The chamber has its unique features such as french style flutes. They were designed to cure the main issue: steel cases tend to expand, but not retract (like brass) sticking to the chamber and making rifle to fail to reload properly especially if gas port is set up too low. Additional drilling was another way to repair the issue for some rifles. If you want to know for sure, check if your rifle has stamp: square with line inside it.
IF someone is inclined to produce some replacement part for SVT, they should do the part pictured below in stainless steel. 99% of those are badly corroded causing general failures.