N scale 4-6-0, side rod on r-hand side falls off

[willyhenry29]

Bought the little loco 2cnd hand but once on the track, the side rod on right hand side fell off. After much fiddling & cursing, managed to get the 2 little sprues on the tiny plastic attachment which the rod connects onto the little "plastic housing" fixed to side of the loco. When placed back on track, was ok, as soon went in reverse , it fell off again..... I see the "attachment"  to which rod must connect is loose from side of the loco whereas on other side its not, i. e . on other side where there is no problem, that attachment is firmly fixed to side of the loco, it is not loose.  After googling , seems this is a issue with this loco. Is there a fix, please? Thanks