NAD 3020 input jack problem

Hi. I purchased a NAD 3020 a month ago. The input jacks worked when I got it, but somehow damaged when I tried to put male cable-It was very hard to connect so I probably put it too strongly.

Right now, only 1 source(tape) is working in both channels. Only 1 channel is working in Aux and Tuner input. Both of them are damaged in right channel input, which are located in deeper position.(You know what I mean if you have had this amp)

How could I fix this myself? Thanks in advance.