>   service movwf   save_w
>          movf    status,w
>          movwf   save_s
...
>          movf    save_s,w
>          movwf   status
>          movf    save_w,w
>          retfie

You will find that this will cause you problems if you start doing
anything in your non-interrupt code that uses the status register.
The problem is that using a movf to restore registers affects the status
register.  You need to change things around to use a swapf instruction:

int:    movwf   save_w
        swapf   status,w
        movwf   save_s
...
        swapf   save_s,w
        movwf   status
        swapf   save_w,f
        swapf   save_w,w
        retfie

This will work on the 61, 71, and 84, but not on parts with bank-switched
registers.