Source of sensor

[sujit_51]

Freinds,
The following photo sensors are transmitter receiver type which is used for detecting moving parts in one piece of machine. I am not able to find the source from where can I get these sensors as one of them has got damaged and I am not able to replace it with suitable alternate.

Part no as written on these sensors are :

1. JU-21P
2.JU-21R

Can any one suggest me the source of these sensors. If not can there be any alternate parts available?

Thanks.

sujit_51