Westy 70

All I know is it’s a loksound 5 decoder

Hi new to sound so took my 20 to a local model shop to have sound fitted and on the whole sounds good .My only problem is when shunting or doing short moves when it accelerates it sounds spot on but coming to a stand still it keeps reving even when the brake sound has come and gone and the Loco has stopped which is strange .I have a factory Bachmann class 20 and the sound works spot on just a better speaker is required any ideas I’ve tried to up load a video but it’s to large for this page thanks