I purchased one many years ago from a now defunct dealer. We cannot locate a model number on the chair and we don't have the receipt. In looking at BY's website, it is similar to The Laredo model 548. I sent a couple of faxes to BY and they have not replied. They don't list an email address or have an 800 number so I suspect they don't like to hear from their customers. The chair will recline and I have to pull it back up while holding the lever to return it to an upright position. Am I at the mercy of a repair guy or how can I identify the correct cylinder so I can do it myself? Many thanks in advance!