Nothing in the cab to check level. You were the only to make a replay and thanks.Not familiar with the T135, but my Thomas 175 has a small glass tube inside the engine compartment (left side) where you can check the level of hydraulic oil. I would start there.
Don't know if this will be of any help this late in the game but my Thomas has two petcocks on the inside wall that holds the hydraulic reservoir. You open the upper petcock and add hydraulic fluid through the fill cap on the top until fluid can be seen flowing out the upper petcock. Then close the upper petcockNothing in the cab to check level. You were the only to make a replay and thanks.