I have purchased one pump from Toyota and 2 from SMH. The Pumps are identical. Manufactured by KYB. I have sent an email to them asking for help. Here is a thought... Clogged return filter?? or maybe the gear in the front cover, is chain driven but has a bearing on the front and back side. Could worn bearings cause the shaft in the pump to wobble enough to cause a failure? The forklift is in route to my shop now. Will start digging into it soon. Not saying the relief valve isn't the cause, but it seems highly unlikely. Have any of you actually seen a relief valve failure?