When i put a disc into the blu-ray disc player

hello! 
theres a problem with the mechanism disk compartment  ie the lens is not being raised up to the position to read disk 
When the disk is being taken in the lens is raised up evenly if  not happen no disk will be red .
pls see if the belts are tight or widen if widen needs replacement  because tray does not activate the lens, are some of reasons why the lens can't read .
2, one should check the spinner (disk mortar) if spinning .
3, pls see that the lens is being moved to start position  by its mechanism
Otherwise ur DVD player is fine only the disk compartment .

good luck