Saving Old Seagulls

i have a model 75 seagull with a insulastic permanent bolt on mounting bracket.
when the engine sits in the bracket with the security bar through it there is a small gap either side so when the engine is running,
she moves from side to side on the bar, is this normal or can i fix a small washer on each side.
model no esc 181.

sorry, model no 181 hh1.

I wouldnt worry about it as mine has done it from new.

My century has end to end play and is a bit sloppy on the pin but under steam sits still. If its shaking bad maybe it's a sign of something running a little rough? Stick some washers in if it helps.